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POSTCONF(5)		      File Formats Manual		   POSTCONF(5)

NAME
       postconf	- Postfix configuration	parameters

SYNOPSIS
       postconf	parameter ...

       postconf	-e "parameter=value" ...

DESCRIPTION
       The  Postfix main.cf configuration file specifies a small subset	of all
       the parameters that control the operation of the	Postfix	 mail  system.
       Parameters not specified	in main.cf are left at their default values.

       The general format of the main.cf file is as follows:

       o      Each  logical line has the form "parameter = value".  Whitespace
	      around the "=" is	ignored, as is whitespace at the end of	a log-
	      ical line.

       o      Empty  lines and whitespace-only lines are ignored, as are lines
	      whose first non-whitespace character is a	`#'.

       o      A	logical	line starts with  non-whitespace  text.	 A  line  that
	      starts with whitespace continues a logical line.

       o      A	parameter value	may refer to other parameters.

	      o	     The  expressions  "$name",	"${name}" or "$(name)" are re-
		     cursively replaced	by the value of	the named parameter.

	      o	     The expression "${name?value}" expands  to	 "value"  when
		     "$name" is	non-empty. This	form is	supported with Postfix
		     version 2.2 and later.

	      o	     The expression "${name:value}" expands  to	 "value"  when
		     "$name"  is  empty.  This	form is	supported with Postfix
		     version 2.2 and later.

	      o	     Specify "$$" to produce a single "$" character.

       o      When the same parameter is defined multiple times, only the last
	      instance is remembered.

       o      Otherwise,  the  order of	main.cf	parameter definitions does not
	      matter.

       The remainder of	this document is a description of all Postfix configu-
       ration parameters. Default values are shown after the parameter name in
       parentheses, and	can be looked up with the "postconf -d"	command.

       Note: this is not an invitation to make changes to  Postfix  configura-
       tion  parameters.  Unnecessary  changes can impair the operation	of the
       mail system.

2bounce_notice_recipient (default: postmaster)
       The recipient of	undeliverable mail that	 cannot	 be  returned  to  the
       sender.	This feature is	enabled	with the notify_classes	parameter.

access_map_defer_code (default:	450)
       The  numerical  Postfix	SMTP server response code for an access(5) map
       "defer" action, including "defer_if_permit" or "defer_if_reject". Prior
       to Postfix 2.6, the response is hard-coded as "450".

       Do  not	change	this  unless  you have a complete understanding	of RFC
       2821.

       This feature is available in Postfix 2.6	and later.

access_map_reject_code (default: 554)
       The numerical Postfix SMTP server response code for  an	access(5)  map
       "reject"	action.

       Do  not	change	this  unless  you have a complete understanding	of RFC
       2821.

address_verify_cache_cleanup_interval (default:	12h)
       The amount of time  between  verify(8)  address	verification  database
       cleanup	runs.  This  feature  requires	that the database supports the
       "delete"	and "sequence" operators.  Specify a zero interval to  disable
       database	cleanup.

       After  each  database cleanup run, the verify(8)	daemon logs the	number
       of entries that were retained and dropped. A cleanup run	is  logged  as
       "partial"  when	the  daemon  terminates	 early after "postfix reload",
       "postfix	stop", or no requests for $max_idle seconds.

       Time units: s (seconds),	m (minutes), h (hours),	d (days), w (weeks).

       This feature is available in Postfix 2.7.

address_verify_default_transport (default: $default_transport)
       Overrides the default_transport parameter setting for address verifica-
       tion probes.

       This feature is available in Postfix 2.1	and later.

address_verify_local_transport (default: $local_transport)
       Overrides  the  local_transport parameter setting for address verifica-
       tion probes.

       This feature is available in Postfix 2.1	and later.

address_verify_map (default: see postconf -d output)
       Lookup table for	persistent address verification	status	storage.   The
       table  is maintained by the verify(8) service, and is opened before the
       process releases	privileges.

       The lookup table	is persistent by  default  (Postfix  2.7  and  later).
       Specify	an empty table name to keep the	information in volatile	memory
       which is	lost after "postfix reload" or "postfix	stop". This is the de-
       fault with Postfix version 2.6 and earlier.

       Specify a location in a file system that	will not fill up. If the data-
       base becomes corrupted, the world comes to an end.  To  recover	delete
       (NOT: truncate) the file	and do "postfix	reload".

       Postfix	daemon	processes do not use root privileges when opening this
       file (Postfix 2.5 and later).  The file must therefore be stored	 under
       a  Postfix-owned	 directory such	as the data_directory.	As a migration
       aid, an attempt to open the file	under a	non-Postfix directory is redi-
       rected to the Postfix-owned data_directory, and a warning is logged.

       Examples:

       address_verify_map = hash:/var/db/postfix/verify
       address_verify_map = btree:/var/db/postfix/verify

       This feature is available in Postfix 2.1	and later.

address_verify_negative_cache (default:	yes)
       Enable caching of failed	address	verification probe results.  When this
       feature is enabled, the cache may pollute quickly with  garbage.	  When
       this  feature  is  disabled, Postfix will generate an address probe for
       every lookup.

       This feature is available in Postfix 2.1	and later.

address_verify_negative_expire_time (default: 3d)
       The time	after which a failed probe expires from	the address  verifica-
       tion cache.

       Time units: s (seconds),	m (minutes), h (hours),	d (days), w (weeks).

       This feature is available in Postfix 2.1	and later.

address_verify_negative_refresh_time (default: 3h)
       The  time  after	 which a failed	address	verification probe needs to be
       refreshed.

       Time units: s (seconds),	m (minutes), h (hours),	d (days), w (weeks).

       This feature is available in Postfix 2.1	and later.

address_verify_poll_count (default: normal: 3, overload: 1)
       How many	times to query the verify(8) service for the completion	of  an
       address verification request in progress.

       By  default,  the Postfix SMTP server polls the verify(8) service up to
       three times under non-overload conditions, and  only  once  when	 under
       overload.  With Postfix version 2.5 and earlier,	the SMTP server	always
       polls the verify(8) service up to three times by	default.

       Specify 1 to implement a	crude form of greylisting, that	is, always de-
       fer the first delivery request for a new	address.

       Examples:

       # Postfix <= 2.6	default
       address_verify_poll_count = 3
       # Poor man's greylisting
       address_verify_poll_count = 1

       This feature is available in Postfix 2.1	and later.

address_verify_poll_delay (default: 3s)
       The delay between queries for the completion of an address verification
       request in progress.

       The default polling delay is 3 seconds.

       Time units: s (seconds),	m (minutes), h (hours),	d (days), w (weeks).

       This feature is available in Postfix 2.1	and later.

address_verify_positive_expire_time (default: 31d)
       The time	after which a successful probe expires from the	address	 veri-
       fication	cache.

       Time units: s (seconds),	m (minutes), h (hours),	d (days), w (weeks).

       This feature is available in Postfix 2.1	and later.

address_verify_positive_refresh_time (default: 7d)
       The  time  after	which a	successful address verification	probe needs to
       be refreshed.  The address verification status is not updated when  the
       probe fails (optimistic caching).

       Time units: s (seconds),	m (minutes), h (hours),	d (days), w (weeks).

       This feature is available in Postfix 2.1	and later.

address_verify_relay_transport (default: $relay_transport)
       Overrides  the  relay_transport parameter setting for address verifica-
       tion probes.

       This feature is available in Postfix 2.1	and later.

address_verify_relayhost (default: $relayhost)
       Overrides the relayhost	parameter  setting  for	 address  verification
       probes. This information	can be overruled with the transport(5) table.

       This feature is available in Postfix 2.1	and later.

address_verify_sender (default:	$double_bounce_sender)
       The  sender  address  to	 use  in address verification probes; prior to
       Postfix 2.5 the default was "postmaster". To avoid  problems  with  ad-
       dress  probes  that are sent in response	to address probes, the Postfix
       SMTP server excludes the	probe sender address  from  all	 SMTPD	access
       blocks.

       Specify	an  empty value	(address_verify_sender =) or <>	if you want to
       use the null sender address. Beware, some sites reject  mail  from  <>,
       even though RFCs	require	that such addresses be accepted.

       Examples:

       address_verify_sender = <>
       address_verify_sender = postmaster@my.domain

       This feature is available in Postfix 2.1	and later.

address_verify_sender_dependent_default_transport_maps	(default:  $sender_de-
       pendent_default_transport_maps)
       Overrides the sender_dependent_default_transport_maps parameter setting
       for address verification	probes.

       This feature is available in Postfix 2.7	and later.

address_verify_sender_dependent_relayhost_maps (default: $sender_dependent_re-
       layhost_maps)
       Overrides the sender_dependent_relayhost_maps parameter setting for ad-
       dress verification probes.

       This feature is available in Postfix 2.3	and later.

address_verify_service_name (default: verify)
       The  name  of  the verify(8) address verification service. This service
       maintains the status of sender and/or  recipient	 address  verification
       probes, and generates probes on request by other	Postfix	processes.

address_verify_transport_maps (default:	$transport_maps)
       Overrides the transport_maps parameter setting for address verification
       probes.

       This feature is available in Postfix 2.1	and later.

address_verify_virtual_transport (default: $virtual_transport)
       Overrides the virtual_transport parameter setting for address verifica-
       tion probes.

       This feature is available in Postfix 2.1	and later.

alias_database (default: see postconf -d output)
       The  alias  databases  for  local(8)  delivery  that  are  updated with
       "newaliases" or with "sendmail -bi".

       This is a separate configuration	parameter because not all  the	tables
       specified with $alias_maps have to be local files.

       Examples:

       alias_database =	hash:/etc/aliases
       alias_database =	hash:/etc/mail/aliases

alias_maps (default: see postconf -d output)
       The alias databases that	are used for local(8) delivery.	See aliases(5)
       for syntax details.

       The default list	is system dependent.  On systems with NIS, the default
       is to search the	local alias database, then the NIS alias database.

       If  you	change	the  alias  database, run "postalias /etc/aliases" (or
       wherever	your system  stores  the  mail	alias  file),  or  simply  run
       "newaliases" to build the necessary DBM or DB file.

       The  local(8)  delivery agent disallows regular expression substitution
       of $1 etc. in alias_maps, because that would open a security hole.

       The local(8) delivery agent will	silently ignore	requests  to  use  the
       proxymap(8)  server  within  alias_maps.	Instead	it will	open the table
       directly. Before	Postfix	version	2.2, the local(8) delivery agent  will
       terminate with a	fatal error.

       Examples:

       alias_maps = hash:/etc/aliases, nis:mail.aliases
       alias_maps = hash:/etc/aliases

allow_mail_to_commands (default: alias,	forward)
       Restrict	 local(8)  mail	delivery to external commands.	The default is
       to disallow delivery to "|command" in :include:	files (see  aliases(5)
       for the text that defines this terminology).

       Specify	zero  or more of: alias, forward or include, in	order to allow
       commands	in aliases(5), .forward	files or in :include:  files,  respec-
       tively.

       Example:

       allow_mail_to_commands =	alias,forward,include

allow_mail_to_files (default: alias, forward)
       Restrict	 local(8)  mail	 delivery to external files. The default is to
       disallow	"/file/name" destinations in :include:	files (see  aliases(5)
       for the text that defines this terminology).

       Specify	zero  or more of: alias, forward or include, in	order to allow
       "/file/name" destinations in aliases(5),	.forward  files	 and  in  :in-
       clude:  files, respectively.

       Example:

       allow_mail_to_files = alias,forward,include

allow_min_user (default: no)
       Allow a sender or recipient address to have `-' as the first character.
       By default, this	is not allowed,	to avoid accidents with	software  that
       passes email addresses via the command line. Such software would	not be
       able to distinguish a malicious address from a bona  fide  command-line
       option.	Although this can be prevented by inserting a "--" option ter-
       minator into the	command	line, this is  difficult  to  enforce  consis-
       tently and globally.

       As  of  Postfix version 2.5, this feature is implemented	by trivial-re-
       write(8).  With	earlier	 versions  this	 feature  was  implemented  by
       qmgr(8) and was limited to recipient addresses only.

allow_percent_hack (default: yes)
       Enable  the rewriting of	the form "user%domain" to "user@domain".  This
       is enabled by default.

       Note: with Postfix version 2.2, message header address  rewriting  hap-
       pens only when one of the following conditions is true:

       o      The message is received with the Postfix sendmail(1) command,

       o      The  message is received from a network client that matches $lo-
	      cal_header_rewrite_clients,

       o      The  message  is	received  from	the  network,  and   the   re-
	      mote_header_rewrite_domain   parameter   specifies  a  non-empty
	      value.

       To  get	the  behavior  before  Postfix	version	 2.2,	specify	  "lo-
       cal_header_rewrite_clients = static:all".

       Example:

       allow_percent_hack = no

allow_untrusted_routing	(default: no)
       Forward	mail  with sender-specified routing (user[@%!]remote[@%!]site)
       from untrusted clients to destinations matching $relay_domains.

       By default, this	feature	is turned off.	This closes a nasty open relay
       loophole	 where	a  backup  MX host can be tricked into forwarding junk
       mail to a primary MX host which then spams it out to the	world.

       This parameter also controls if non-local addresses with	 sender-speci-
       fied  routing  can  match  Postfix  access tables. By default, such ad-
       dresses cannot match Postfix access tables, because the address is  am-
       biguous.

alternate_config_directories (default: empty)
       A  list	of  non-default	 Postfix configuration directories that	may be
       specified with "-c config_directory" on the command line,  or  via  the
       MAIL_CONFIG environment parameter.

       This list must be specified in the default Postfix configuration	direc-
       tory, and is used by set-gid Postfix commands such as postqueue(1)  and
       postdrop(1).

always_add_missing_headers (default: no)
       Always  add (Resent-) From:, To:, Date: or Message-ID: headers when not
       present.	 Postfix 2.6 and later add these  headers  only	 when  clients
       match  the  local_header_rewrite_clients	 parameter  setting.   Earlier
       Postfix versions	always add these headers; this may break  DKIM	signa-
       tures that cover	non-existent headers.

always_bcc (default: empty)
       Optional	 address  that	receives a "blind carbon copy" of each message
       that is received	by the Postfix mail system.

       Note: if	mail to	the BCC	address	bounces	it will	 be  returned  to  the
       sender.

       Note:  automatic	 BCC  recipients  are  produced	only for new mail.  To
       avoid mailer loops, automatic BCC recipients are	 not  generated	 after
       Postfix	forwards  mail internally, or after Postfix generates mail it-
       self.

anvil_rate_time_unit (default: 60s)
       The time	unit over which	client connection rates	and  other  rates  are
       calculated.

       This  feature is	implemented by the anvil(8) service which is available
       in Postfix version 2.2 and later.

       The default interval is relatively short. Because of the	high frequency
       of updates, the anvil(8)	server uses volatile memory only. Thus,	infor-
       mation is lost whenever the process terminates.

       Time units: s (seconds),	m (minutes), h (hours),	d (days),  w  (weeks).
       The default time	unit is	s (seconds).

anvil_status_update_time (default: 600s)
       How  frequently	the  anvil(8) connection and rate limiting server logs
       peak usage information.

       This feature is available in Postfix 2.2	and later.

       Time units: s (seconds),	m (minutes), h (hours),	d (days),  w  (weeks).
       The default time	unit is	s (seconds).

append_at_myorigin (default: yes)
       With locally submitted mail, append the string "@$myorigin" to mail ad-
       dresses without domain information. With	remotely submitted  mail,  ap-
       pend the	string "@$remote_header_rewrite_domain"	instead.

       Note  1:	this feature is	enabled	by default and must not	be turned off.
       Postfix does not	support	domain-less addresses.

       Note 2: with Postfix version 2.2, message header	address	rewriting hap-
       pens only when one of the following conditions is true:

       o      The message is received with the Postfix sendmail(1) command,

       o      The  message is received from a network client that matches $lo-
	      cal_header_rewrite_clients,

       o      The  message  is	received  from	the  network,  and   the   re-
	      mote_header_rewrite_domain   parameter   specifies  a  non-empty
	      value.

       To  get	the  behavior  before  Postfix	version	 2.2,	specify	  "lo-
       cal_header_rewrite_clients = static:all".

append_dot_mydomain (default: yes)
       With  locally  submitted	 mail,	append	the string ".$mydomain"	to ad-
       dresses that have no ".domain"  information.  With  remotely  submitted
       mail, append the	string ".$remote_header_rewrite_domain"	instead.

       Note 1: this feature is enabled by default. If disabled,	users will not
       be able to send mail to "user@partialdomainname"	but will have to spec-
       ify full	domain names instead.

       Note 2: with Postfix version 2.2, message header	address	rewriting hap-
       pens only when one of the following conditions is true:

       o      The message is received with the Postfix sendmail(1) command,

       o      The message is received from a network client that matches  $lo-
	      cal_header_rewrite_clients,

       o      The   message   is  received  from  the  network,	 and  the  re-
	      mote_header_rewrite_domain  parameter  specifies	 a   non-empty
	      value.

       To   get	  the  behavior	 before	 Postfix  version  2.2,	 specify  "lo-
       cal_header_rewrite_clients = static:all".

application_event_drain_time (default: 100s)
       How long	the postkick(1)	command	waits  for  a  request	to  enter  the
       server's	input buffer before giving up.

       Time  units:  s (seconds), m (minutes), h (hours), d (days), w (weeks).
       The default time	unit is	s (seconds).

       This feature is available in Postfix 2.1	and later.

authorized_flush_users (default: static:anyone)
       List of users who are authorized	to flush the queue.

       By default, all users are allowed to flush the queue.  Access is	always
       granted if the invoking user is the super-user or the $mail_owner user.
       Otherwise, the real UID of the process is looked	up in the system pass-
       word  file,  and	access is granted only if the corresponding login name
       is on the access	list.  The username "unknown" is  used	for  processes
       whose real UID is not found in the password file.

       Specify	a  list	 of user names,	"/file/name" or	"type:table" patterns,
       separated by commas and/or whitespace. The  list	 is  matched  left  to
       right,  and the search stops on the first match.	A "/file/name" pattern
       is replaced by its contents; a "type:table"  lookup  table  is  matched
       when  a name matches a lookup key (the lookup result is ignored).  Con-
       tinue long lines	by starting the	next  line  with  whitespace.  Specify
       "!pattern"  to  exclude a name from the list. The form "!/file/name" is
       supported only in Postfix version 2.4 and later.

       This feature is available in Postfix 2.2	and later.

authorized_mailq_users (default: static:anyone)
       List of users who are authorized	to view	the queue.

       By default, all users are allowed to view the queue.  Access is	always
       granted if the invoking user is the super-user or the $mail_owner user.
       Otherwise, the real UID of the process is looked	up in the system pass-
       word  file,  and	access is granted only if the corresponding login name
       is on the access	list.  The username "unknown" is  used	for  processes
       whose real UID is not found in the password file.

       Specify	a  list	 of user names,	"/file/name" or	"type:table" patterns,
       separated by commas and/or whitespace. The  list	 is  matched  left  to
       right,  and the search stops on the first match.	A "/file/name" pattern
       is replaced by its contents; a "type:table"  lookup  table  is  matched
       when  a name matches a lookup key (the lookup result is ignored).  Con-
       tinue long lines	by starting the	next  line  with  whitespace.  Specify
       "!pattern" to exclude a user name from the list.	The form "!/file/name"
       is supported only in Postfix version 2.4	and later.

       This feature is available in Postfix 2.2	and later.

authorized_submit_users	(default: static:anyone)
       List of users who are authorized	to submit mail	with  the  sendmail(1)
       command (and with the privileged	postdrop(1) helper command).

       By  default, all	users are allowed to submit mail.  Otherwise, the real
       UID of the process is looked up in the system password file, and	access
       is  granted only	if the corresponding login name	is on the access list.
       The username "unknown" is used for processes  whose  real  UID  is  not
       found in	the password file. To deny mail	submission access to all users
       specify an empty	list.

       Specify a list of user names, "/file/name"  or  "type:table"  patterns,
       separated  by  commas  and/or  whitespace.  The list is matched left to
       right, and the search stops on the first	match. A "/file/name"  pattern
       is  replaced  by	 its  contents;	a "type:table" lookup table is matched
       when a name matches a lookup key	(the lookup result is ignored).	  Con-
       tinue  long  lines  by  starting	the next line with whitespace. Specify
       "!pattern" to exclude a user name from the list.	The form "!/file/name"
       is supported only in Postfix version 2.4	and later.

       Example:

       authorized_submit_users = !www, static:all

       This feature is available in Postfix 2.2	and later.

authorized_verp_clients	(default: $mynetworks)
       What  SMTP clients are allowed to specify the XVERP command.  This com-
       mand requests that mail be delivered one	recipient at a time with a per
       recipient return	address.

       By default, only	trusted	clients	are allowed to specify XVERP.

       This  parameter	was introduced with Postfix version 1.1.  Postfix ver-
       sion 2.1	renamed	this parameter	to  smtpd_authorized_verp_clients  and
       changed the default to none.

       Specify	a list of network/netmask patterns, separated by commas	and/or
       whitespace. The mask specifies the number of bits in the	 network  part
       of a host address. You can also specify hostnames or .domain names (the
       initial	dot  causes  the  domain  to  match  any   name	  below	  it),
       "/file/name"  or	 "type:table" patterns.	 A "/file/name"	pattern	is re-
       placed by its contents; a "type:table" lookup table is matched  when  a
       table  entry  matches  a	 lookup	string (the lookup result is ignored).
       Continue	long lines by starting the next	line with whitespace.  Specify
       "!pattern"  to  exclude	an address or network block from the list. The
       form "!/file/name" is supported only in Postfix version 2.4 and later.

       Note: IP	version	6 address information must be specified	inside	[]  in
       the   authorized_verp_clients   value,  and  in	files  specified  with
       "/file/name".  IP version 6 addresses contain the  ":"  character,  and
       would otherwise be confused with	a "type:table" pattern.

backwards_bounce_logfile_compatibility (default: yes)
       Produce	additional bounce(8) logfile records that can be read by Post-
       fix versions before 2.0.	The current and	more extensible	"name =	value"
       format  is  needed in order to implement	more sophisticated functional-
       ity.

       This feature is available in Postfix 2.1	and later.

berkeley_db_create_buffer_size (default: 16777216)
       The per-table I/O buffer	size for programs that create Berkeley DB hash
       or btree	tables.	 Specify a byte	count.

       This feature is available in Postfix 2.0	and later.

berkeley_db_read_buffer_size (default: 131072)
       The  per-table  I/O buffer size for programs that read Berkeley DB hash
       or btree	tables.	 Specify a byte	count.

       This feature is available in Postfix 2.0	and later.

best_mx_transport (default: empty)
       Where the Postfix SMTP client should deliver mail  when	it  detects  a
       "mail  loops back to myself" error condition. This happens when the lo-
       cal MTA is the best SMTP	mail exchanger for a destination not listed in
       $mydestination, $inet_interfaces, $proxy_interfaces, $virtual_alias_do-
       mains, or  $virtual_mailbox_domains.   By  default,  the	 Postfix  SMTP
       client returns such mail	as undeliverable.

       Specify,	for example, "best_mx_transport	= local" to pass the mail from
       the Postfix SMTP	client to the local(8) delivery	agent. You can specify
       any message delivery "transport"	or "transport:nexthop" that is defined
       in the master.cf	file. See the transport(5) manual page for the	syntax
       and meaning of "transport" or "transport:nexthop".

       However,	 this  feature	is expensive because it	ties up	a Postfix SMTP
       client process while the	local(8) delivery agent	is doing its work.  It
       is  more	 efficient (for	Postfix) to list all hosted domains in a table
       or database.

biff (default: yes)
       Whether or not to use the local biff service.  This service sends  "new
       mail"  notifications  to	users who have requested new mail notification
       with the	UNIX command "biff y".

       For compatibility reasons this feature is on by	default.   On  systems
       with  lots  of interactive users, the biff service can be a performance
       drain.  Specify "biff = no" in main.cf to disable.

body_checks (default: empty)
       Optional	lookup tables for  content  inspection	as  specified  in  the
       body_checks(5) manual page.

       Note: with Postfix versions before 2.0, these rules inspect all content
       after the primary message headers.

body_checks_size_limit (default: 51200)
       How much	text in	a message body segment (or attachment, if  you	prefer
       to  use	that term) is subjected	to body_checks inspection.  The	amount
       of text is limited to avoid scanning huge attachments.

       This feature is available in Postfix 2.0	and later.

bounce_notice_recipient	(default: postmaster)
       The recipient of	postmaster notifications with the message  headers  of
       mail  that Postfix did not deliver and of SMTP conversation transcripts
       of mail that Postfix did	not receive.  This feature is enabled with the
       notify_classes parameter.

bounce_queue_lifetime (default:	5d)
       The maximal time	a bounce message is queued before it is	considered un-
       deliverable.  By	default, this is the same as the queue life  time  for
       regular mail.

       Time  units:  s (seconds), m (minutes), h (hours), d (days), w (weeks).
       The default time	unit is	d (days).

       Specify 0 when mail delivery should be tried only once.

       This feature is available in Postfix 2.1	and later.

bounce_service_name (default: bounce)
       The name	of the bounce(8) service. This service maintains a  record  of
       failed delivery attempts	and generates non-delivery notifications.

       This feature is available in Postfix 2.0	and later.

bounce_size_limit (default: 50000)
       The  maximal  amount of original	message	text that is sent in a non-de-
       livery notification. Specify a byte count.  A message  is  returned  as
       either message/rfc822 (the complete original) or	as text/rfc822-headers
       (the headers only).  With Postfix version 2.4 and earlier, a message is
       always  returned	as message/rfc822 and is truncated when	it exceeds the
       size limit.

       Notes:

       o      If you  increase	this  limit,  then  you	 should	 increase  the
	      mime_nesting_limit value proportionally.

       o      Be  careful  when	making changes.	 Excessively large values will
	      result in	the loss of non-delivery notifications,	when a	bounce
	      message size exceeds a local or remote MTA's message size	limit.

bounce_template_file (default: empty)
       Pathname	 of a configuration file with bounce message templates.	 These
       override	the built-in templates of delivery status  notification	 (DSN)
       messages	for undeliverable mail,	for delayed mail, successful delivery,
       or delivery verification. The bounce(5) manual page  describes  how  to
       edit and	test template files.

       Template	message	body text may contain $name references to Postfix con-
       figuration parameters. The result of $name expansion can	 be  previewed
       with "postconf -b file_name" before the file is placed into the Postfix
       configuration directory.

       This feature is available in Postfix 2.3	and later.

broken_sasl_auth_clients (default: no)
       Enable inter-operability	with SMTP clients that implement  an  obsolete
       version	of  the	 AUTH command (RFC 4954). Examples of such clients are
       MicroSoft Outlook Express version 4 and MicroSoft Exchange version 5.0.

       Specify "broken_sasl_auth_clients = yes"	to have	Postfix	advertise AUTH
       support in a non-standard way.

canonical_classes      (default:      envelope_sender,	   envelope_recipient,
       header_sender, header_recipient)
       What addresses are subject to canonical_maps address mapping.   By  de-
       fault, canonical_maps address mapping is	applied	to envelope sender and
       recipient addresses, and	to header  sender  and	header	recipient  ad-
       dresses.

       Specify	 one   or   more   of:	 envelope_sender,  envelope_recipient,
       header_sender, header_recipient

       This feature is available in Postfix 2.2	and later.

canonical_maps (default: empty)
       Optional	address	mapping	lookup tables  for  message  headers  and  en-
       velopes.	The mapping is applied to both sender and recipient addresses,
       in both envelopes and  in  headers,  as	controlled  with  the  canoni-
       cal_classes  parameter.	This  is  typically used to clean up dirty ad-
       dresses from legacy mail	systems, or to replace login names  by	First-
       name.Lastname.	The table format and lookups are documented in canoni-
       cal(5). For an overview of Postfix address manipulations	 see  the  AD-
       DRESS_REWRITING_README document.

       If  you use this	feature, run "postmap /etc/postfix/canonical" to build
       the necessary DBM or DB file after every	change.	The changes  will  be-
       come  visible  after a minute or	so.  Use "postfix reload" to eliminate
       the delay.

       Note: with Postfix version 2.2, message header address mapping  happens
       only when message header	address	rewriting is enabled:

       o      The message is received with the Postfix sendmail(1) command,

       o      The  message is received from a network client that matches $lo-
	      cal_header_rewrite_clients,

       o      The  message  is	received  from	the  network,  and   the   re-
	      mote_header_rewrite_domain   parameter   specifies  a  non-empty
	      value.

       To  get	the  behavior  before  Postfix	version	 2.2,	specify	  "lo-
       cal_header_rewrite_clients = static:all".

       Examples:

       canonical_maps =	dbm:/etc/postfix/canonical
       canonical_maps =	hash:/etc/postfix/canonical

cleanup_service_name (default: cleanup)
       The  name  of  the  cleanup(8) service. This service rewrites addresses
       into the	standard form, and performs canonical(5) address  mapping  and
       virtual(5) aliasing.

       This feature is available in Postfix 2.0	and later.

command_directory (default: see	postconf -d output)
       The location of all postfix administrative commands.

command_execution_directory (default: empty)
       The  local(8) delivery agent working directory for delivery to external
       command.	 Failure to change directory causes the	 delivery  to  be  de-
       ferred.

       The  following $name expansions are done	on command_execution_directory
       before the directory is changed.	Expansion happens in  the  context  of
       the  delivery  request.	The result of $name expansion is filtered with
       the character set that is specified with	the execution_directory_expan-
       sion_filter parameter.

       $user  The recipient's username.

       $shell The recipient's login shell pathname.

       $home  The recipient's home directory.

       $recipient
	      The full recipient address.

       $extension
	      The optional recipient address extension.

       $domain
	      The recipient domain.

       $local The entire recipient localpart.

       $recipient_delimiter
	      The system-wide recipient	address	extension delimiter.

       ${name?value}
	      Expands to value when $name is non-empty.

       ${name:value}
	      Expands to value when $name is empty.

       Instead of $name	you can	also specify ${name} or	$(name).

       This feature is available in Postfix 2.2	and later.

command_expansion_filter (default: see postconf	-d output)
       Restrict	 the  characters  that	the  local(8) delivery agent allows in
       $name expansions	of $mailbox_command and	 $command_execution_directory.
       Characters outside the allowed set are replaced by underscores.

command_time_limit (default: 1000s)
       Time limit for delivery to external commands. This limit	is used	by the
       local(8)	delivery agent,	and is the default time	limit for delivery  by
       the pipe(8) delivery agent.

       Note:  if  you set this time limit to a large value you must update the
       global ipc_timeout parameter as well.

config_directory (default: see postconf	-d output)
       The default location of the Postfix main.cf and master.cf configuration
       files. This can be overruled via	the following mechanisms:

       o      The  MAIL_CONFIG environment variable (daemon processes and com-
	      mands).

       o      The "-c" command-line option (commands only).

       With Postfix command that run with set-gid privileges, a	 config_direc-
       tory  override requires either root privileges, or it requires that the
       directory is listed with	the alternate_config_directories parameter  in
       the default main.cf file.

connection_cache_protocol_timeout (default: 5s)
       Time  limit  for	 connection cache connect, send	or receive operations.
       The time	limit is enforced in the client.

       This feature is available in Postfix 2.3	and later.

connection_cache_service_name (default:	scache)
       The name	of the scache(8) connection cache service.  This service main-
       tains a limited pool of cached sessions.

       This feature is available in Postfix 2.2	and later.

connection_cache_status_update_time (default: 600s)
       How  frequently the scache(8) server logs usage statistics with connec-
       tion cache hit and miss rates for logical destinations and for physical
       endpoints.

connection_cache_ttl_limit (default: 2s)
       The  maximal  time-to-live  value  that	the scache(8) connection cache
       server allows. Requests that specify a larger TTL will be  stored  with
       the  maximum  allowed TTL. The purpose of this additional control is to
       protect the infrastructure against careless people. The	cache  TTL  is
       already bounded by $max_idle.

content_filter (default: empty)
       After  the  message is queued, send the entire message to the specified
       transport:destination. The transport name specifies the first field  of
       a  mail delivery	agent definition in master.cf; the syntax of the next-
       hop destination is described in the manual page	of  the	 corresponding
       delivery	 agent.	 More information about	external content filters is in
       the Postfix FILTER_README file.

       Notes:

       o      This setting has lower precedence	than a FILTER action  that  is
	      specified	 in  an	 access(5), header_checks(5) or	body_checks(5)
	      table.

       o      The meaning of an	empty next-hop filter destination  is  version
	      dependent.  Postfix 2.7 and later	will use the recipient domain;
	      earlier versions will use	 $myhostname.	Specify	 "default_fil-
	      ter_nexthop = $myhostname" for compatibility with	Postfix	2.6 or
	      earlier, or specify a  content_filter  value  with  an  explicit
	      next-hop destination.

cyrus_sasl_config_path (default: empty)
       Search  path  for Cyrus SASL application	configuration files, currently
       used only to locate the $smtpd_sasl_path.conf file.   Specify  zero  or
       more  directories  separated by a colon character, or an	empty value to
       use Cyrus SASL's	built-in search	path.

       This feature is available in Postfix 2.5	and later when	compiled  with
       Cyrus SASL 2.1.22 or later.

daemon_directory (default: see postconf	-d output)
       The directory with Postfix support programs and daemon programs.	 These
       should not be invoked directly by humans. The directory must  be	 owned
       by root.

daemon_timeout (default: 18000s)
       How much	time a Postfix daemon process may take to handle a request be-
       fore it is terminated by	a built-in watchdog timer.

       Time units: s (seconds),	m (minutes), h (hours),	d (days),  w  (weeks).
       The default time	unit is	s (seconds).

data_directory (default: see postconf -d output)
       The  directory  with  Postfix-writable data files (for example: caches,
       pseudo-random numbers).	This directory must be owned by	the mail_owner
       account,	and must not be	shared with non-Postfix	software.

       This feature is available in Postfix 2.5	and later.

debug_peer_level (default: 2)
       The  increment  in verbose logging level	when a remote client or	server
       matches a pattern in the	debug_peer_list	parameter.

debug_peer_list	(default: empty)
       Optional	list of	remote client or server	hostname  or  network  address
       patterns	that cause the verbose logging level to	increase by the	amount
       specified in $debug_peer_level.

       Specify domain names, network/netmask patterns,	"/file/name"  patterns
       or   "type:table"  lookup  tables.  The	right-hand  side  result  from
       "type:table" lookups is ignored.

       Pattern matching	of  domain  names  is  controlled  by  the  parent_do-
       main_matches_subdomains parameter.

       Examples:

       debug_peer_list = 127.0.0.1
       debug_peer_list = example.com

debugger_command (default: empty)
       The  external  command  to execute when a Postfix daemon	program	is in-
       voked with the -D option.

       Use "command .. & sleep 5" so that the debugger can attach  before  the
       process	marches	 on. If	you use	an X-based debugger, be	sure to	set up
       your XAUTHORITY environment variable before starting Postfix.

       Example:

       debugger_command	=
	   PATH=/usr/bin:/usr/X11R6/bin
	   ddd $daemon_directory/$process_name $process_id & sleep 5

default_database_type (default:	see postconf -d	output)
       The default database type for use in  newaliases(1),  postalias(1)  and
       postmap(1)  commands.  On  many UNIX systems the	default	type is	either
       dbm or hash. The	default	setting	is frozen when the Postfix  system  is
       built.

       Examples:

       default_database_type = hash
       default_database_type = dbm

default_delivery_slot_cost (default: 5)
       How  often  the Postfix queue manager's scheduler is allowed to preempt
       delivery	of one message with another.

       Each transport maintains	a so-called "available delivery	slot  counter"
       for  each message. One message can be preempted by another one when the
       other message can be delivered using no more delivery slots (i.e.,  in-
       vocations  of delivery agents) than the current message counter has ac-
       cumulated (or will eventually accumulate	- see about slot loans below).
       This  parameter controls	how often is the counter incremented - it hap-
       pens after each default_delivery_slot_cost recipients have been	deliv-
       ered.

       The  cost of 0 is used to disable the preempting	scheduling completely.
       The minimum value the scheduling	algorithm can use is 2 - use it	if you
       want to maximize	the message throughput rate. Although there is no max-
       imum, it	doesn't	make much sense	to use values above say	50.

       The only	reason why the value of	2 is not the default is	the  way  this
       parameter affects the delivery of mailing-list mail. In the worst case,
       their  delivery	can   take   somewhere	 between   (cost+1/cost)   and
       (cost/cost-1) times more	than if	the preemptive scheduler was disabled.
       The default value of 5 turns out	to provide reasonable message response
       times while making sure the mailing-list	deliveries are not extended by
       more than 20-25 percent even in the worst case.

       Use transport_delivery_slot_cost	to specify a transport-specific	 over-
       ride,  where  transport	is  the	master.cf name of the message delivery
       transport.

       Examples:

       default_delivery_slot_cost = 0
       default_delivery_slot_cost = 2

default_delivery_slot_discount (default: 50)
       The default value for transport-specific	 _delivery_slot_discount  set-
       tings.

       This  parameter speeds up the moment when a message preemption can hap-
       pen. Instead of waiting until the full amount  of  delivery  slots  re-
       quired  is  available,  the preemption can happen when transport_deliv-
       ery_slot_discount percent of the	required amount	plus  transport_deliv-
       ery_slot_loan  still  remains  to  be  accumulated.  Note that the full
       amount will still have to be accumulated	before another preemption  can
       take place later.

       Use  transport_delivery_slot_discount  to  specify a transport-specific
       override, where transport is the	master.cf name of the message delivery
       transport.

default_delivery_slot_loan (default: 3)
       The default value for transport-specific	_delivery_slot_loan settings.

       This  parameter speeds up the moment when a message preemption can hap-
       pen. Instead of waiting until the full amount  of  delivery  slots  re-
       quired  is  available,  the preemption can happen when transport_deliv-
       ery_slot_discount percent of the	required amount	plus  transport_deliv-
       ery_slot_loan  still  remains  to  be  accumulated.  Note that the full
       amount will still have to be accumulated	before another preemption  can
       take place later.

       Use  transport_delivery_slot_loan to specify a transport-specific over-
       ride, where transport is	the master.cf name  of	the  message  delivery
       transport.

default_destination_concurrency_failed_cohort_limit (default: 1)
       How many	pseudo-cohorts must suffer connection or handshake failure be-
       fore a specific destination is considered unavailable (and further  de-
       livery  is suspended). Specify zero to disable this feature. A destina-
       tion's pseudo-cohort failure count is reset each	time a	delivery  com-
       pletes without connection or handshake failure for that specific	desti-
       nation.

       A pseudo-cohort is the number of	deliveries equal  to  a	 destination's
       delivery	concurrency.

       Use  transport_destination_concurrency_failed_cohort_limit to specify a
       transport-specific override, where transport is the master.cf  name  of
       the message delivery transport.

       This  feature  is available in Postfix 2.5. The default setting is com-
       patible with earlier Postfix versions.

default_destination_concurrency_limit (default:	20)
       The default maximal number of parallel deliveries to the	same  destina-
       tion.  This is the default limit	for delivery via the lmtp(8), pipe(8),
       smtp(8) and virtual(8) delivery agents.	With per-destination recipient
       limit > 1, a destination	is a domain, otherwise it is a recipient.

       Use transport_destination_concurrency_limit to specify a	transport-spe-
       cific override, where transport is the master.cf	name  of  the  message
       delivery	transport.

default_destination_concurrency_negative_feedback (default: 1)
       The  per-destination  amount of delivery	concurrency negative feedback,
       after a delivery	completes with	a  connection  or  handshake  failure.
       Feedback	 values	 are  in the range 0..1	inclusive. With	negative feed-
       back, concurrency is decremented	at the	beginning  of  a  sequence  of
       length  1/feedback. This	is unlike positive feedback, where concurrency
       is incremented at the end of a sequence of length 1/feedback.

       As of Postfix version 2.5, negative  feedback  cannot  reduce  delivery
       concurrency  to	zero.	Instead, a destination is marked dead (further
       delivery	suspended) after the failed pseudo-cohort count	 reaches  $de-
       fault_destination_concurrency_failed_cohort_limit (or $transport_desti-
       nation_concurrency_failed_cohort_limit).	 To make  the  scheduler  com-
       pletely	immune	to  connection	or  handshake failures,	specify	a zero
       feedback	value and a zero failed	pseudo-cohort limit.

       Specify one of the following forms:

       number

       number /	number
	      Constant feedback. The value must	be in the  range  0..1	inclu-
	      sive.   The  default  setting  of	"1" is compatible with Postfix
	      versions before 2.5, where a destination's delivery  concurrency
	      is throttled down	to zero	(and further delivery suspended) after
	      a	single failed pseudo-cohort.

       number /	concurrency
	      Variable feedback	of "number  /  (delivery  concurrency)".   The
	      number must be in	the range 0..1 inclusive. With number equal to
	      "1", a destination's delivery concurrency	is  decremented	 by  1
	      after each failed	pseudo-cohort.

       A  pseudo-cohort	 is  the number	of deliveries equal to a destination's
       delivery	concurrency.

       Use transport_destination_concurrency_negative_feedback	to  specify  a
       transport-specific  override,  where transport is the master.cf name of
       the message delivery transport.

       This feature is available in Postfix 2.5. The default setting  is  com-
       patible with earlier Postfix versions.

default_destination_concurrency_positive_feedback (default: 1)
       The  per-destination  amount of delivery	concurrency positive feedback,
       after a delivery	completes without  connection  or  handshake  failure.
       Feedback	 values	 are in	the range 0..1 inclusive.  The concurrency in-
       creases until it	reaches	the per-destination maximal concurrency	limit.
       With  positive feedback,	concurrency is incremented at the end of a se-
       quence with length 1/feedback. This is unlike negative feedback,	 where
       concurrency is decremented at the start of a sequence of	length 1/feed-
       back.

       Specify one of the following forms:

       number

       number /	number
	      Constant feedback.  The value must be in the range  0..1	inclu-
	      sive. The	default	setting	of "1" is compatible with Postfix ver-
	      sions before 2.5,	where  a  destination's	 delivery  concurrency
	      doubles after each successful pseudo-cohort.

       number /	concurrency
	      Variable	feedback  of  "number  / (delivery concurrency)".  The
	      number must be in	the range 0..1 inclusive. With number equal to
	      "1",  a  destination's  delivery concurrency is incremented by 1
	      after each successful pseudo-cohort.

       A pseudo-cohort is the number of	deliveries equal  to  a	 destination's
       delivery	concurrency.

       Use  transport_destination_concurrency_positive_feedback	 to  specify a
       transport-specific override, where transport is the master.cf  name  of
       the message delivery transport.

       This feature is available in Postfix 2.5	and later.

default_destination_rate_delay (default: 0s)
       The  default amount of delay that is inserted between individual	deliv-
       eries to	the same destination; with per-destination recipient  limit  >
       1, a destination	is a domain, otherwise it is a recipient.

       To  enable  the delay, specify a	non-zero time value (an	integral value
       plus an optional	one-letter suffix that specifies the time unit).

       Time units: s (seconds),	m (minutes), h (hours),	d (days),  w  (weeks).
       The default time	unit is	s (seconds).

       NOTE: the delay is enforced by the queue	manager. The delay timer state
       does not	survive	"postfix reload" or "postfix stop".

       Use transport_destination_rate_delay to	specify	 a  transport-specific
       override, where transport is the	master.cf name of the message delivery
       transport.

       NOTE: with a non-zero _destination_rate_delay, specify a	transport_des-
       tination_concurrency_failed_cohort_limit	of 10 or more to prevent Post-
       fix from	deferring all mail for the same	 destination  after  only  one
       connection or handshake error.

       This feature is available in Postfix 2.5	and later.

default_destination_recipient_limit (default: 50)
       The default maximal number of recipients	per message delivery.  This is
       the default limit for delivery via the lmtp(8),	pipe(8),  smtp(8)  and
       virtual(8) delivery agents.

       Setting	this parameter to a value of 1 changes the meaning of the cor-
       responding per-destination concurrency limit from concurrency  per  do-
       main into concurrency per recipient.

       Use  transport_destination_recipient_limit  to specify a	transport-spe-
       cific override, where transport is the master.cf	name  of  the  message
       delivery	transport.

default_extra_recipient_limit (default:	1000)
       The default value for the extra per-transport limit imposed on the num-
       ber of in-memory	recipients.  This extra	recipient  space  is  reserved
       for  the	 cases when the	Postfix	queue manager's	scheduler preempts one
       message with another and	suddenly needs some extra recipients slots for
       the chosen message in order to avoid performance	degradation.

       Use  transport_extra_recipient_limit  to	 specify  a transport-specific
       override, where transport is the	master.cf name of the message delivery
       transport.

default_filter_nexthop (default: empty)
       When  a content_filter or FILTER	request	specifies no explicit next-hop
       destination, use	$default_filter_nexthop	instead; when  that  value  is
       empty,  use the domain in the recipient address.	 Specify "default_fil-
       ter_nexthop = $myhostname" for compatibility with Postfix  version  2.6
       and earlier, or specify an explicit next-hop destination	with each con-
       tent_filter value or FILTER action.

       This feature is available in Postfix 2.7	and later.

default_minimum_delivery_slots (default: 3)
       How many	recipients a message must have in order	to invoke the  Postfix
       queue  manager's	 scheduling  algorithm	at  all.  Messages which would
       never accumulate	at least this many delivery  slots  (subject  to  slot
       cost parameter as well) are never preempted.

       Use  transport_minimum_delivery_slots  to  specify a transport-specific
       override, where transport is the	master.cf name of the message delivery
       transport.

default_privs (default:	nobody)
       The  default rights used	by the local(8)	delivery agent for delivery to
       external	file or	command.  These	rights are used	when delivery  is  re-
       quested from an aliases(5) file that is owned by	root, or when delivery
       is done on behalf of root. DO NOT SPECIFY  A  PRIVILEGED	 USER  OR  THE
       POSTFIX OWNER.

default_process_limit (default:	100)
       The  default  maximal  number of	Postfix	child processes	that provide a
       given service. This limit can be	overruled for specific services	in the
       master.cf file.

default_rbl_reply (default: see	postconf -d output)
       The  default  SMTP  server  response template for a request that	is re-
       jected by an RBL-based restriction. This	template can be	 overruled  by
       specific	entries	in the optional	rbl_reply_maps lookup table.

       This feature is available in Postfix 2.0	and later.

       The template is subject to exactly one level of $name substitution:

       $client
	      The client hostname and IP address, formatted as name[address].

       $client_address
	      The client IP address.

       $client_name
	      The    client    hostname	   or	 "unknown".   See   reject_un-
	      known_client_hostname for	more details.

       $reverse_client_name
	      The client hostname from	address->name  lookup,	or  "unknown".
	      See reject_unknown_reverse_client_hostname for more details.

       $helo_name
	      The hostname given in HELO or EHLO command or empty string.

       $rbl_class
	      The  blacklisted	entity type: Client host, Helo command,	Sender
	      address, or Recipient address.

       $rbl_code
	      The  numerical  SMTP  response  code,  as	 specified  with   the
	      maps_rbl_reject_code  configuration parameter. Note: The numeri-
	      cal SMTP response	code is	required, and must appear at the start
	      of  the  reply. With Postfix version 2.3 and later this informa-
	      tion may be followed by an RFC 3463 enhanced status code.

       $rbl_domain
	      The RBL domain where $rbl_what is	blacklisted.

       $rbl_reason
	      The reason why $rbl_what is blacklisted, or an empty string.

       $rbl_what
	      The entity that is blacklisted (an IP address, a hostname, a do-
	      main name, or an email address whose domain was blacklisted).

       $recipient
	      The recipient address or <> in case of the null address.

       $recipient_domain
	      The recipient domain or empty string.

       $recipient_name
	      The recipient address localpart or <> in case of null address.

       $sender
	      The sender address or <> in case of the null address.

       $sender_domain
	      The sender domain	or empty string.

       $sender_name
	      The sender address localpart or <> in case of the	null address.

       ${name?text}
	      Expands to `text'	if $name is not	empty.

       ${name:text}
	      Expands to `text'	if $name is empty.

       Instead of $name	you can	also specify ${name} or	$(name).

       Note:  when  an	enhanced status	code is	specified in an	RBL reply tem-
       plate, it is subject to modification.   The  following  transformations
       are  needed  when the same RBL reply template is	used for client, helo,
       sender, or recipient access restrictions.

       o      When rejecting a sender address, the Postfix  SMTP  server  will
	      transform	 a  recipient  DSN status (e.g., 4.1.1-4.1.6) into the
	      corresponding sender DSN status, and vice	versa.

       o      When rejecting non-address information (such as the HELO command
	      argument	or  the	 client	 hostname/address),  the  Postfix SMTP
	      server will transform a sender or	recipient DSN  status  into  a
	      generic non-address DSN status (e.g., 4.0.0).

default_recipient_limit	(default: 20000)
       The default per-transport upper limit on	the number of in-memory	recip-
       ients.  These limits take priority over the global qmgr_message_recipi-
       ent_limit  after	the message has	been assigned to the respective	trans-
       ports.  See also	default_extra_recipient_limit and qmgr_message_recipi-
       ent_minimum.

       Use transport_recipient_limit to	specify	a transport-specific override,
       where transport is the master.cf	name of	the  message  delivery	trans-
       port.

default_recipient_refill_delay (default: 5s)
       The  default  per-transport  maximum  delay between recipients refills.
       When not	all message recipients fit into	the memory at once, keep load-
       ing  more  of them at least once	every this many	seconds.  This is used
       to make sure the	recipients are refilled	in  timely  manner  even  when
       $default_recipient_refill_limit is too high for too slow	deliveries.

       Use  transport_recipient_refill_delay  to  specify a transport-specific
       override, where transport is the	master.cf name of the message delivery
       transport.

       This feature is available in Postfix 2.4	and later.

default_recipient_refill_limit (default: 100)
       The default per-transport limit on the number of	recipients refilled at
       once.  When not all message recipients fit into	the  memory  at	 once,
       keep  loading  more of them in batches of at least this many at a time.
       See also	$default_recipient_refill_delay, which may result in recipient
       batches lower than this when this limit is too high for too slow	deliv-
       eries.

       Use transport_recipient_refill_limit to	specify	 a  transport-specific
       override, where transport is the	master.cf name of the message delivery
       transport.

       This feature is available in Postfix 2.4	and later.

default_transport (default: smtp)
       The default mail	delivery transport and next-hop	destination for	desti-
       nations	that do	not match $mydestination, $inet_interfaces, $proxy_in-
       terfaces,  $virtual_alias_domains,  $virtual_mailbox_domains,  or  $re-
       lay_domains.   This information can be overruled	with the sender_depen-
       dent_default_transport_maps parameter and with the transport(5) table.

       In order	of decreasing precedence, the  nexthop	destination  is	 taken
       from    $sender_dependent_default_transport_maps,   $default_transport,
       $sender_dependent_relayhost_maps, $relayhost, or	from the recipient do-
       main.

       Specify	a string of the	form transport:nexthop,	where transport	is the
       name of a mail delivery transport defined in master.cf.	 The  :nexthop
       destination is optional;	its syntax is documented in the	manual page of
       the corresponding delivery agent.

       Example:

       default_transport = uucp:relayhostname

default_verp_delimiters	(default: +=)
       The two default VERP delimiter characters. These	are used when  no  ex-
       plicit delimiters are specified with the	SMTP XVERP command or with the
       "sendmail -V" command-line option. Specify characters that are  allowed
       by the verp_delimiter_filter setting.

       This feature is available in Postfix 1.1	and later.

defer_code (default: 450)
       The  numerical  Postfix	SMTP  server  response code when a remote SMTP
       client request is rejected by the "defer" restriction.

       Do not change this unless you have  a  complete	understanding  of  RFC
       2821.

defer_service_name (default: defer)
       The  name  of  the  defer  service.  This service is implemented	by the
       bounce(8) daemon	and maintains a	record of failed delivery attempts and
       generates non-delivery notifications.

       This feature is available in Postfix 2.0	and later.

defer_transports (default: empty)
       The  names  of message delivery transports that should not deliver mail
       unless someone issues "sendmail -q" or equivalent. Specify zero or more
       names  of mail delivery transports names	that appear in the first field
       of master.cf.

       Example:

       defer_transports	= smtp

delay_logging_resolution_limit (default: 2)
       The maximal number of digits after the decimal point when logging  sub-
       second delay values.  Specify a number in the range 0..6.

       Large delay values are rounded off to an	integral number	seconds; delay
       values below the	delay_logging_resolution_limit are logged as "0",  and
       small delay values are logged with at most two-digit precision.

       The format of the "delays=a/b/c/d" logging is as	follows:

       o      a	= time from message arrival to last active queue entry

       o      b	= time from last active	queue entry to connection setup

       o      c	= time in connection setup, including DNS, EHLO	and STARTTLS

       o      d	= time in message transmission

       This feature is available in Postfix 2.3	and later.

delay_notice_recipient (default: postmaster)
       The  recipient  of postmaster notifications with	the message headers of
       mail that cannot	be delivered within $delay_warning_time	time units.

       This feature is enabled with the	delay_warning_time parameter.

delay_warning_time (default: 0h)
       The time	after which the	sender receives	the message  headers  of  mail
       that is still queued.

       To  enable  this	 feature,  specify  a non-zero time value (an integral
       value plus an optional one-letter suffix	that specifies the time	unit).

       Time units: s (seconds),	m (minutes), h (hours),	d (days),  w  (weeks).
       The default time	unit is	h (hours).

deliver_lock_attempts (default:	20)
       The  maximal number of attempts to acquire an exclusive lock on a mail-
       box file	or bounce(8) logfile.

deliver_lock_delay (default: 1s)
       The time	between	attempts to acquire an exclusive  lock	on  a  mailbox
       file or bounce(8) logfile.

       Time  units:  s (seconds), m (minutes), h (hours), d (days), w (weeks).
       The default time	unit is	s (seconds).

destination_concurrency_feedback_debug (default: no)
       Make the	queue manager's	feedback  algorithm  verbose  for  performance
       analysis	purposes.

       This feature is available in Postfix 2.5	and later.

detect_8bit_encoding_header (default: yes)
       Automatically detect 8BITMIME body content by looking at	Content-Trans-
       fer-Encoding: message headers; historically, this  behavior  was	 hard-
       coded to	be "always on".

       This feature is available in Postfix 2.5	and later.

disable_dns_lookups (default: no)
       Disable	DNS  lookups  in  the Postfix SMTP and LMTP clients. When dis-
       abled, hosts are	looked up with the getaddrinfo() system	 library  rou-
       tine which normally also	looks in /etc/hosts.

       DNS lookups are enabled by default.

disable_mime_input_processing (default:	no)
       Turn  off MIME processing while receiving mail. This means that no spe-
       cial treatment is given to Content-Type:	message	headers, and that  all
       text  after the initial message headers is considered to	be part	of the
       message body.

       This feature is available in Postfix 2.0	and later.

       Mime input processing is	enabled	by default, and	is needed in order  to
       recognize MIME headers in message content.

disable_mime_output_conversion (default: no)
       Disable	the conversion of 8BITMIME format to 7BIT format.  Mime	output
       conversion is needed when the destination does not  advertise  8BITMIME
       support.

       This feature is available in Postfix 2.0	and later.

disable_verp_bounces (default: no)
       Disable sending one bounce report per recipient.

       The default, one	per recipient, is what ezmlm needs.

       This feature is available in Postfix 1.1	and later.

disable_vrfy_command (default: no)
       Disable	the SMTP VRFY command. This stops some techniques used to har-
       vest email addresses.

       Example:

       disable_vrfy_command = no

dnsblog_reply_delay (default: 0s)
       A debugging aid to artifically delay DNS	responses.

       This feature is available in Postfix 2.8.

dnsblog_service_name (default: dnsblog)
       The name	of the dnsblog(8) service entry	 in  master.cf.	 This  service
       performs	DNS white/blacklist lookups.

       This feature is available in Postfix 2.8	and later.

dont_remove (default: 0)
       Don't remove queue files	and save them to the "saved" mail queue.  This
       is a debugging aid.  To inspect the envelope information	and content of
       a Postfix queue file, use the postcat(1)	command.

double_bounce_sender (default: double-bounce)
       The  sender  address  of	postmaster notifications that are generated by
       the mail	system.	All mail to this address is silently discarded,	in or-
       der to terminate	mail bounce loops.

duplicate_filter_limit (default: 1000)
       The  maximal  number  of	 addresses remembered by the address duplicate
       filter for aliases(5) or	virtual(5) alias expansion,  or	 for  showq(8)
       queue displays.

empty_address_default_transport_maps_lookup_key	(default: <>)
       The  sender_dependent_default_transport_maps search string that will be
       used instead of the null	sender address.

       This feature is available in Postfix 2.7	and later.

empty_address_recipient	(default: MAILER-DAEMON)
       The recipient of	mail addressed to the null address.  Postfix does  not
       accept  such  addresses in SMTP commands, but they may still be created
       locally as the result of	configuration or software error.

empty_address_relayhost_maps_lookup_key	(default: <>)
       The sender_dependent_relayhost_maps search string that will be used in-
       stead of	the null sender	address.

       This  feature  is available in Postfix 2.5 and later. With earlier ver-
       sions, sender_dependent_relayhost_maps lookups  were  skipped  for  the
       null sender address.

enable_errors_to (default: no)
       Report mail delivery errors to the address specified with the non-stan-
       dard Errors-To: message header, instead of the envelope sender  address
       (this feature is	removed	with Postfix version 2.2, is turned off	by de-
       fault with Postfix version 2.1, and is  always  turned  on  with	 older
       Postfix versions).

enable_original_recipient (default: yes)
       Enable  support	for  the  X-Original-To	message	header.	This header is
       needed for multi-recipient mailboxes.

       When this parameter is set to yes, the cleanup(8) daemon	 performs  du-
       plicate elimination on distinct pairs of	(original recipient, rewritten
       recipient), and	generates  non-empty  original	recipient  queue  file
       records.

       When this parameter is set to no, the cleanup(8)	daemon performs	dupli-
       cate elimination	on the rewritten recipient address only, and generates
       empty original recipient	queue file records.

       This  feature  is available in Postfix 2.1 and later. With Postfix ver-
       sion 2.0, support for the X-Original-To message header is always	turned
       on.  Postfix  versions before 2.0 have no support for the X-Original-To
       message header.

error_notice_recipient (default: postmaster)
       The recipient of	postmaster notifications about mail delivery  problems
       that  are  caused  by  policy,  resource,  software or protocol errors.
       These notifications are enabled with the	notify_classes parameter.

error_service_name (default: error)
       The name	of the error(8)	pseudo delivery	agent. This service always re-
       turns mail as undeliverable.

       This feature is available in Postfix 2.0	and later.

execution_directory_expansion_filter (default: see postconf -d output)
       Restrict	 the  characters  that	the  local(8) delivery agent allows in
       $name expansions	of $command_execution_directory.   Characters  outside
       the allowed set are replaced by underscores.

       This feature is available in Postfix 2.2	and later.

expand_owner_alias (default: no)
       When  delivering	 to an alias "aliasname" that has an "owner-aliasname"
       companion alias,	set the	envelope sender	address	to  the	 expansion  of
       the "owner-aliasname" alias. Normally, Postfix sets the envelope	sender
       address to the name of the "owner-aliasname" alias.

export_environment (default: see postconf -d output)
       The list	of environment variables that a	Postfix	process	will export to
       non-Postfix  processes. The TZ variable is needed for sane time keeping
       on System-V-ish systems.

       Specify a list of names and/or name=value pairs,	 separated  by	white-
       space  or  comma. The name=value	form is	supported with Postfix version
       2.1 and later.

       Example:

       export_environment = TZ PATH=/bin:/usr/bin

extract_recipient_limit	(default: 10240)
       The maximal number of recipient addresses  that	Postfix	 will  extract
       from message headers when mail is submitted with	"sendmail -t".

       This feature was	removed	in Postfix version 2.1.

fallback_relay (default: empty)
       Optional	 list of relay hosts for SMTP destinations that	can't be found
       or that are unreachable.	With Postfix 2.3 this parameter	is renamed  to
       smtp_fallback_relay.

       By  default,  mail  is returned to the sender when a destination	is not
       found, and delivery is deferred when a destination is unreachable.

       The fallback relays must	be SMTP	destinations. Specify a	domain,	 host,
       host:port,  [host]:port,	 [address]  or [address]:port; the form	[host]
       turns off MX lookups.  If you specify multiple SMTP destinations, Post-
       fix will	try them in the	specified order.

       Note:  before  Postfix  2.2, do not use the fallback_relay feature when
       relaying	mail for a backup or primary MX	domain.	Mail  would  loop  be-
       tween  the  Postfix  MX host and	the fallback_relay host	when the final
       destination is unavailable.

       o      In main.cf specify "relay_transport = relay",

       o      In master.cf specify "-o fallback_relay =" (i.e.,	empty) at  the
	      end of the relay entry.

       o      In transport maps, specify "relay:nexthop..."  as	the right-hand
	      side for backup or primary MX domain entries.

       Postfix version 2.2 and later will not use the  fallback_relay  feature
       for destinations	that it	is MX host for.

fallback_transport (default: empty)
       Optional	 message  delivery  transport that the local(8)	delivery agent
       should use for names that are not found in the aliases(5) or UNIX pass-
       word database.

       The  precedence	of  local(8)  delivery	features  from high to low is:
       aliases,	 .forward  files,  mailbox_transport_maps,  mailbox_transport,
       mailbox_command_maps,  mailbox_command, home_mailbox, mail_spool_direc-
       tory, fallback_transport_maps, fallback_transport and luser_relay.

fallback_transport_maps	(default: empty)
       Optional	lookup tables with per-recipient message  delivery  transports
       for  recipients	that the local(8) delivery agent could not find	in the
       aliases(5) or UNIX password database.

       The precedence of local(8) delivery  features  from  high  to  low  is:
       aliases,	 .forward  files,  mailbox_transport_maps,  mailbox_transport,
       mailbox_command_maps, mailbox_command, home_mailbox,  mail_spool_direc-
       tory, fallback_transport_maps, fallback_transport and luser_relay.

       For  safety  reasons, this feature does not allow $number substitutions
       in regular expression maps.

       This feature is available in Postfix 2.3	and later.

fast_flush_domains (default: $relay_domains)
       Optional	list of	destinations that  are	eligible  for  per-destination
       logfiles	with mail that is queued to those destinations.

       By  default,  Postfix maintains "fast flush" logfiles only for destina-
       tions that the Postfix SMTP server is willing to	relay to (i.e. the de-
       fault  is: "fast_flush_domains =	$relay_domains"; see the relay_domains
       parameter in the	postconf(5) manual).

       Specify a list of hosts or domains, "/file/name"	patterns or  "type:ta-
       ble"  lookup  tables,  separated	by commas and/or whitespace.  Continue
       long lines by starting the next line with  whitespace.  A  "/file/name"
       pattern	is  replaced  by  its contents;	a "type:table" lookup table is
       matched when the	domain or its parent domain appears as lookup key.

       Specify "fast_flush_domains =" (i.e., empty) to disable the feature al-
       together.

fast_flush_purge_time (default:	7d)
       The  time  after	which an empty per-destination "fast flush" logfile is
       deleted.

       You can specify the time	as a number, or	as a number followed by	a let-
       ter  that  indicates  the  time	unit:  s=seconds,  m=minutes, h=hours,
       d=days, w=weeks.	 The default time unit is days.

fast_flush_refresh_time	(default: 12h)
       The time	after which  a	non-empty  but	unread	per-destination	 "fast
       flush"  logfile	needs  to be refreshed.	 The contents of a logfile are
       refreshed by requesting delivery	of all messages	listed in the logfile.

       You can specify the time	as a number, or	as a number followed by	a let-
       ter  that  indicates  the  time	unit:  s=seconds,  m=minutes, h=hours,
       d=days, w=weeks.	 The default time unit is hours.

fault_injection_code (default: 0)
       Force specific internal tests to	fail, to test the handling  of	errors
       that are	difficult to reproduce otherwise.

flush_service_name (default: flush)
       The  name  of the flush(8) service. This	service	maintains per-destina-
       tion logfiles with the queue file names of  mail	 that  is  queued  for
       those destinations.

       This feature is available in Postfix 2.0	and later.

fork_attempts (default:	5)
       The maximal number of attempts to fork()	a child	process.

fork_delay (default: 1s)
       The delay between attempts to fork() a child process.

       Time  units:  s (seconds), m (minutes), h (hours), d (days), w (weeks).
       The default time	unit is	s (seconds).

forward_expansion_filter (default: see postconf	-d output)
       Restrict	the characters that the	 local(8)  delivery  agent  allows  in
       $name  expansions of $forward_path.  Characters outside the allowed set
       are replaced by underscores.

forward_path (default: see postconf -d output)
       The local(8) delivery agent search list for  finding  a	.forward  file
       with  user-specified  delivery methods. The first file that is found is
       used.

       The following $name expansions are  done	 on  forward_path  before  the
       search actually happens.	The result of $name expansion is filtered with
       the character set that is specified with	 the  forward_expansion_filter
       parameter.

       $user  The recipient's username.

       $shell The recipient's login shell pathname.

       $home  The recipient's home directory.

       $recipient
	      The full recipient address.

       $extension
	      The optional recipient address extension.

       $domain
	      The recipient domain.

       $local The entire recipient localpart.

       $recipient_delimiter
	      The system-wide recipient	address	extension delimiter.

       ${name?value}
	      Expands to value when $name is non-empty.

       ${name:value}
	      Expands to value when $name is empty.

       Instead of $name	you can	also specify ${name} or	$(name).

       Examples:

       forward_path = /var/forward/$user
       forward_path =
	   /var/forward/$user/.forward$recipient_delimiter$extension,
	   /var/forward/$user/.forward

frozen_delivered_to (default: yes)
       Update  the local(8) delivery agent's idea of the Delivered-To: address
       (see prepend_delivered_header) only once, at the	start  of  a  delivery
       attempt;	 do  not  update  the  Delivered-To:  address  while expanding
       aliases or .forward files.

       This feature is available in Postfix 2.3	and later. With	older  Postfix
       releases,  the behavior is as if	this parameter is set to "no". The old
       setting can be expensive	with deeply nested aliases or .forward	files.
       When  an	 alias	or .forward file changes the Delivered-To: address, it
       ties up one queue file and one cleanup process instance while  mail  is
       being forwarded.

hash_queue_depth (default: 1)
       The number of subdirectory levels for queue directories listed with the
       hash_queue_names	parameter.

       After changing the hash_queue_names or hash_queue_depth parameter, exe-
       cute the	command	"postfix reload".

hash_queue_names (default: deferred, defer)
       The names of queue directories that are split across multiple subdirec-
       tory levels.

       Before Postfix version 2.2, the default list of hashed queues was  sig-
       nificantly  larger. Claims about	improvements in	file system technology
       suggest that hashing of the incoming and	active	queues	is  no	longer
       needed.	Fewer  hashed  directories speed up the	time needed to restart
       Postfix.

       After changing the hash_queue_names or hash_queue_depth parameter, exe-
       cute the	command	"postfix reload".

header_address_token_limit (default: 10240)
       The  maximal number of address tokens are allowed in an address message
       header. Information that	exceeds	the limit is discarded.	 The limit  is
       enforced	by the cleanup(8) server.

header_checks (default:	empty)
       Optional	 lookup	tables for content inspection of primary non-MIME mes-
       sage headers, as	specified in the header_checks(5) manual page.

header_size_limit (default: 102400)
       The maximal amount of memory in bytes for storing a message header.  If
       a  header is larger, the	excess is discarded.  The limit	is enforced by
       the cleanup(8) server.

helpful_warnings (default: yes)
       Log warnings about  problematic	configuration  settings,  and  provide
       helpful suggestions.

       This feature is available in Postfix 2.0	and later.

home_mailbox (default: empty)
       Optional	 pathname of a mailbox file relative to	a local(8) user's home
       directory.

       Specify a pathname ending in "/"	for qmail-style	delivery.

       The precedence of local(8) delivery  features  from  high  to  low  is:
       aliases,	 .forward  files,  mailbox_transport_maps,  mailbox_transport,
       mailbox_command_maps, mailbox_command, home_mailbox,  mail_spool_direc-
       tory, fallback_transport_maps, fallback_transport and luser_relay.

       Examples:

       home_mailbox = Mailbox
       home_mailbox = Maildir/

hopcount_limit (default: 50)
       The maximal number of Received:	message	headers	that is	allowed	in the
       primary message headers.	A message that exceeds the limit  is  bounced,
       in order	to stop	a mailer loop.

html_directory (default: see postconf -d output)
       The  location of	Postfix	HTML files that	describe how to	build, config-
       ure or operate a	specific Postfix subsystem or feature.

ignore_mx_lookup_error (default: no)
       Ignore DNS MX lookups that produce no response.	By default, the	 Post-
       fix SMTP	client defers delivery and tries again after some delay.  This
       behavior	is required by the SMTP	standard.

       Specify "ignore_mx_lookup_error = yes" to force a DNS A	record	lookup
       instead.	This violates the SMTP standard	and can	result in mis-delivery
       of mail.

import_environment (default: see postconf -d output)
       The list	of environment parameters that a Postfix process  will	import
       from a non-Postfix parent process. Examples of relevant parameters:

       TZ     Needed for sane time keeping on most System-V-ish	systems.

       DISPLAY
	      Needed for debugging Postfix daemons with	an X-windows debugger.

       XAUTHORITY
	      Needed for debugging Postfix daemons with	an X-windows debugger.

       MAIL_CONFIG
	      Needed to	make "postfix -c" work.

       Specify	a  list	 of names and/or name=value pairs, separated by	white-
       space or	comma. The name=value form is supported	with  Postfix  version
       2.1 and later.

in_flow_delay (default:	1s)
       Time  to	pause before accepting a new message, when the message arrival
       rate exceeds the	message	delivery rate. This feature is	turned	on  by
       default (it's disabled on SCO UNIX due to an SCO	bug).

       With  the  default  100 SMTP server process limit, "in_flow_delay = 1s"
       limits the mail inflow to 100 messages per second above the  number  of
       messages	delivered per second.

       Specify 0 to disable the	feature. Valid delays are 0..10.

inet_interfaces	(default: all)
       The network interface addresses that this mail system receives mail on.
       Specify "all" to	receive	mail on	all network interfaces (default),  and
       "loopback-only"	to  receive  mail  on loopback network interfaces only
       (Postfix	version	2.2 and	later).	 The parameter also controls  delivery
       of mail to user@[ip.address].

       Note 1: you need	to stop	and start Postfix when this parameter changes.

       Note 2: address information may be enclosed inside [], but this form is
       not required here.

       When inet_interfaces specifies just one IPv4 and/or IPv6	 address  that
       is  not	a  loopback address, the Postfix SMTP client will use this ad-
       dress as	the IP source address for outbound mail. Support for  IPv6  is
       available in Postfix version 2.2	and later.

       On  a multi-homed firewall with separate	Postfix	instances listening on
       the "inside" and	"outside" interfaces, this can prevent	each  instance
       from  being  able to reach servers on the "other	side" of the firewall.
       Setting smtp_bind_address to 0.0.0.0 avoids the potential  problem  for
       IPv4, and setting smtp_bind_address6 to :: solves the problem for IPv6.

       A better	solution for multi-homed firewalls is to leave inet_interfaces
       at the default value and	instead	use explicit IP	addresses in the  mas-
       ter.cf  SMTP  server  definitions.   This  preserves  the  Postfix SMTP
       client's	loop detection,	by ensuring that each  side  of	 the  firewall
       knows  that  the	 other	IP  address  is	 still	the same host. Setting
       $inet_interfaces	to a single IPv4 and/or	IPV6 address is	primarily use-
       ful  with  virtual  hosting  of domains on secondary IP addresses, when
       each IP address serves a	different domain (and has a different $myhost-
       name setting).

       See also	the proxy_interfaces parameter,	for network addresses that are
       forwarded to Postfix by way of a	proxy or address translator.

       Examples:

       inet_interfaces = all (DEFAULT)
       inet_interfaces = loopback-only (Postfix	version	2.2 and	later)
       inet_interfaces = 127.0.0.1
       inet_interfaces = 127.0.0.1, [::1] (Postfix version 2.2 and later)
       inet_interfaces = 192.168.1.2, 127.0.0.1

inet_protocols (default: ipv4)
       The Internet protocols Postfix will attempt to use when making  or  ac-
       cepting connections. Specify one	or more	of "ipv4" or "ipv6", separated
       by whitespace or	commas.	The form "all" is equivalent to	 "ipv4,	 ipv6"
       or "ipv4", depending on whether the operating system implements IPv6.

       This feature is available in Postfix 2.2	and later.

       Note: you MUST stop and start Postfix after changing this parameter.

       On systems that pre-date	IPV6_V6ONLY support (RFC 3493),	an IPv6	server
       will also accept	IPv4 connections, even when IPv4 is  turned  off  with
       the  inet_protocols  parameter.	 On  systems with IPV6_V6ONLY support,
       Postfix will use	separate server	sockets	for IPv6 and  IPv4,  and  each
       will accept only	connections for	the corresponding protocol.

       When  IPv4 support is enabled via the inet_protocols parameter, Postfix
       will to DNS type	A record lookups, and will convert IPv4-in-IPv6	client
       IP  addresses  (::ffff:1.2.3.4)	to their original IPv4 form (1.2.3.4).
       The latter is needed on hosts that pre-date  IPV6_V6ONLY	 support  (RFC
       3493).

       When  IPv6 support is enabled via the inet_protocols parameter, Postfix
       will do DNS type	AAAA record lookups.

       When both IPv4 and IPv6 support are enabled, the	 Postfix  SMTP	client
       will attempt to connect via IPv6	before attempting to use IPv4.

       Examples:

       inet_protocols =	ipv4 (DEFAULT)
       inet_protocols =	all
       inet_protocols =	ipv6
       inet_protocols =	ipv4, ipv6

initial_destination_concurrency	(default: 5)
       The  initial per-destination concurrency	level for parallel delivery to
       the same	destination.  With per-destination recipient limit > 1,	a des-
       tination	is a domain, otherwise it is a recipient.

       Use  transport_initial_destination_concurrency  to specify a transport-
       specific	override, where	transport is the master.cf name	of the message
       delivery	transport (Postfix 2.5 and later).

       Warning:	 with concurrency of 1,	one bad	message	can be enough to block
       all mail	to a site.

internal_mail_filter_classes (default: empty)
       What categories of Postfix-generated mail are subject  to  before-queue
       content inspection by non_smtpd_milters,	header_checks and body_checks.
       Specify zero or more of	the  following,	 separated  by	whitespace  or
       comma.

       bounce Inspect the content of delivery status notifications.

       notify Inspect  the  content of postmaster notifications	by the smtp(8)
	      and smtpd(8) processes.

       NOTE: It's generally not	safe to	enable content inspection of  Postfix-
       generated email messages. The user is warned.

       This feature is available in Postfix 2.3	and later.

invalid_hostname_reject_code (default: 501)
       The numerical Postfix SMTP server response code when the	client HELO or
       EHLO command parameter is rejected by the  reject_invalid_helo_hostname
       restriction.

       Do  not	change	this  unless  you have a complete understanding	of RFC
       2821.

ipc_idle (default: version dependent)
       The time	after which a client closes  an	 idle  internal	 communication
       channel.	  The purpose is to allow servers to terminate voluntarily af-
       ter they	become idle. This is used, for example,	by the address resolv-
       ing and rewriting clients.

       With Postfix 2.4	the default value was reduced from 100s	to 5s.

       Time  units:  s (seconds), m (minutes), h (hours), d (days), w (weeks).
       The default time	unit is	s (seconds).

ipc_timeout (default: 3600s)
       The time	limit for sending or receiving information  over  an  internal
       communication  channel.	The purpose is to break	out of deadlock	situa-
       tions. If the time limit	is exceeded the	software aborts	with  a	 fatal
       error.

       Time  units:  s (seconds), m (minutes), h (hours), d (days), w (weeks).
       The default time	unit is	s (seconds).

ipc_ttl	(default: 1000s)
       The time	after which a client closes an active  internal	 communication
       channel.	  The purpose is to allow servers to terminate voluntarily af-
       ter reaching their client limit.	 This is used, for example, by the ad-
       dress resolving and rewriting clients.

       Time  units:  s (seconds), m (minutes), h (hours), d (days), w (weeks).
       The default time	unit is	s (seconds).

       This feature is available in Postfix 2.1	and later.

line_length_limit (default: 2048)
       Upon input, long	lines are chopped up  into  pieces  of	at  most  this
       length; upon delivery, long lines are reconstructed.

lmtp_address_preference	(default: ipv6)
       The  LMTP-specific version of the smtp_address_preference configuration
       parameter.  See there for details.

       This feature is available in Postfix 2.8	and later.

lmtp_assume_final (default: no)
       When an LMTP server announces no	DSN support, assume  that  the	server
       performs	final delivery,	and send "delivered" delivery status notifica-
       tions instead of	"relayed". The default setting is backwards compatible
       to  avoid the infinetisimal possibility of breaking existing LMTP-based
       content filters.

lmtp_bind_address (default: empty)
       The LMTP-specific version of the	smtp_bind_address configuration	param-
       eter.  See there	for details.

       This feature is available in Postfix 2.3	and later.

lmtp_bind_address6 (default: empty)
       The  LMTP-specific  version of the smtp_bind_address6 configuration pa-
       rameter.	 See there for details.

       This feature is available in Postfix 2.3	and later.

lmtp_body_checks (default: empty)
       The LMTP-specific version of the	smtp_body_checks configuration parame-
       ter. See	there for details.

       This feature is available in Postfix 2.5	and later.

lmtp_cache_connection (default:	yes)
       Keep  Postfix LMTP client connections open for up to $max_idle seconds.
       When the	LMTP client receives a request for  the	 same  connection  the
       connection is reused.

       This  parameter	is available in	Postfix	version	2.2 and	earlier.  With
       Postfix version 2.3  and	 later,	 see  lmtp_connection_cache_on_demand,
       lmtp_connection_cache_destinations,	  or	   lmtp_connection_re-
       use_time_limit.

       The effectiveness of cached connections will be determined by the  num-
       ber of LMTP servers in use, and the concurrency limit specified for the
       LMTP client. Cached connections are closed under	any of	the  following
       conditions:

       o      The LMTP client idle time	limit is reached.  This	limit is spec-
	      ified with the Postfix max_idle configuration parameter.

       o      A	delivery request specifies a different	destination  than  the
	      one currently cached.

       o      The  per-process	limit  on  the	number of delivery requests is
	      reached.	This limit is specified	with the Postfix max_use  con-
	      figuration parameter.

       o      Upon  the	onset of another delivery request, the LMTP server as-
	      sociated with the	current	session	does not respond to  the  RSET
	      command.

       Most  of	 these	limitations will be removed after Postfix implements a
       connection cache	that is	shared among multiple LMTP client programs.

lmtp_cname_overrides_servername	(default: yes)
       The LMTP-specific version of the	 smtp_cname_overrides_servername  con-
       figuration parameter.  See there	for details.

       This feature is available in Postfix 2.3	and later.

lmtp_connect_timeout (default: 0s)
       The  LMTP  client  time	limit for completing a TCP connection, or zero
       (use the	operating system built-in time limit).	When no	connection can
       be  made	within the deadline, the LMTP client tries the next address on
       the mail	exchanger list.

       Time units: s (seconds),	m (minutes), h (hours),	d (days),  w  (weeks).
       The default time	unit is	s (seconds).

       Example:

       lmtp_connect_timeout = 30s

lmtp_connection_cache_destinations (default: empty)
       The  LMTP-specific  version  of	the smtp_connection_cache_destinations
       configuration parameter.	 See there for details.

       This feature is available in Postfix 2.3	and later.

lmtp_connection_cache_on_demand	(default: yes)
       The LMTP-specific version of the	 smtp_connection_cache_on_demand  con-
       figuration parameter.  See there	for details.

       This feature is available in Postfix 2.3	and later.

lmtp_connection_cache_time_limit (default: 2s)
       The  LMTP-specific version of the smtp_connection_cache_time_limit con-
       figuration parameter.  See there	for details.

       This feature is available in Postfix 2.3	and later.

lmtp_connection_reuse_time_limit (default: 300s)
       The LMTP-specific version of the	smtp_connection_reuse_time_limit  con-
       figuration parameter.  See there	for details.

       This feature is available in Postfix 2.3	and later.

lmtp_data_done_timeout (default: 600s)
       The  LMTP client	time limit for sending the LMTP	".", and for receiving
       the server response.  When no response is received within the deadline,
       a warning is logged that	the mail may be	delivered multiple times.

       Time  units:  s (seconds), m (minutes), h (hours), d (days), w (weeks).
       The default time	unit is	s (seconds).

lmtp_data_init_timeout (default: 120s)
       The LMTP	client time limit for sending the LMTP DATA command,  and  for
       receiving the server response.

       Time  units:  s (seconds), m (minutes), h (hours), d (days), w (weeks).
       The default time	unit is	s (seconds).

lmtp_data_xfer_timeout (default: 180s)
       The LMTP	client time limit for sending the LMTP message content.	  When
       the  connection	stalls	for more than $lmtp_data_xfer_timeout the LMTP
       client terminates the transfer.

       Time units: s (seconds),	m (minutes), h (hours),	d (days),  w  (weeks).
       The default time	unit is	s (seconds).

lmtp_defer_if_no_mx_address_found (default: no)
       The LMTP-specific version of the	smtp_defer_if_no_mx_address_found con-
       figuration parameter.  See there	for details.

       This feature is available in Postfix 2.3	and later.

lmtp_destination_concurrency_limit   (default:	  $default_destination_concur-
       rency_limit)
       The  maximal  number of parallel	deliveries to the same destination via
       the lmtp	message	delivery transport. This  limit	 is  enforced  by  the
       queue  manager.	The message delivery transport name is the first field
       in the entry in the master.cf file.

lmtp_destination_recipient_limit    (default:	  $default_destination_recipi-
       ent_limit)
       The  maximal  number of recipients per message for the lmtp message de-
       livery transport. This limit is enforced	by the queue manager. The mes-
       sage  delivery  transport  name	is the first field in the entry	in the
       master.cf file.

       Setting this parameter to a value of 1 changes the meaning of lmtp_des-
       tination_concurrency_limit from concurrency per domain into concurrency
       per recipient.

lmtp_discard_lhlo_keyword_address_maps (default: empty)
       Lookup tables, indexed by the remote LMTP server	address, with case in-
       sensitive  lists	 of  LHLO  keywords (pipelining, starttls, auth, etc.)
       that the	LMTP client will ignore	in the LHLO  response  from  a	remote
       LMTP  server.  See lmtp_discard_lhlo_keywords for details. The table is
       not indexed by hostname for  consistency	 with  smtpd_discard_ehlo_key-
       word_address_maps.

       This feature is available in Postfix 2.3	and later.

lmtp_discard_lhlo_keywords (default: empty)
       A  case	insensitive list of LHLO keywords (pipelining, starttls, auth,
       etc.) that the LMTP client will ignore in the LHLO response from	a  re-
       mote LMTP server.

       This feature is available in Postfix 2.3	and later.

       Notes:

       o      Specify the silent-discard pseudo	keyword	to prevent this	action
	      from being logged.

       o      Use the lmtp_discard_lhlo_keyword_address_maps feature  to  dis-
	      card LHLO	keywords selectively.

lmtp_dns_resolver_options (default: empty)
       The  LMTP-specific  version of the smtp_dns_resolver_options configura-
       tion parameter.	See there for details.

       This feature is available in Postfix 2.8	and later.

lmtp_enforce_tls (default: no)
       The LMTP-specific version of the	smtp_enforce_tls configuration parame-
       ter.  See there for details.

       This feature is available in Postfix 2.3	and later.

lmtp_generic_maps (default: empty)
       The LMTP-specific version of the	smtp_generic_maps configuration	param-
       eter.  See there	for details.

       This feature is available in Postfix 2.3	and later.

lmtp_header_checks (default: empty)
       The LMTP-specific version of the	smtp_header_checks  configuration  pa-
       rameter.	See there for details.

       This feature is available in Postfix 2.5	and later.

lmtp_host_lookup (default: dns)
       The LMTP-specific version of the	smtp_host_lookup configuration parame-
       ter.  See there for details.

       This feature is available in Postfix 2.3	and later.

lmtp_lhlo_name (default: $myhostname)
       The hostname to send in the LMTP	LHLO command.

       The default value is the	 machine  hostname.   Specify  a  hostname  or
       [ip.add.re.ss].

       This  information  can  be  specified  in the main.cf file for all LMTP
       clients,	or it can be specified in the master.cf	file  for  a  specific
       client, for example:

	   /etc/postfix/master.cf:
	       mylmtp ... lmtp -o lmtp_lhlo_name=foo.bar.com

       This feature is available in Postfix 2.3	and later.

lmtp_lhlo_timeout (default: 300s)
       The  LMTP  client  time limit for sending the LHLO command, and for re-
       ceiving the initial server response.

       Time units: s (seconds),	m (minutes), h (hours),	d (days),  w  (weeks).
       The default time	unit is	s (seconds).

lmtp_line_length_limit (default: 990)
       The  LMTP-specific  version of the smtp_line_length_limit configuration
       parameter.  See there for details.

       This feature is available in Postfix 2.3	and later.

lmtp_mail_timeout (default: 300s)
       The LMTP	client time limit for sending the MAIL FROM command,  and  for
       receiving the server response.

       Time  units:  s (seconds), m (minutes), h (hours), d (days), w (weeks).
       The default time	unit is	s (seconds).

lmtp_mime_header_checks	(default: empty)
       The LMTP-specific version of the	smtp_mime_header_checks	 configuration
       parameter. See there for	details.

       This feature is available in Postfix 2.5	and later.

lmtp_mx_address_limit (default:	5)
       The  LMTP-specific  version  of the smtp_mx_address_limit configuration
       parameter.  See there for details.

       This feature is available in Postfix 2.3	and later.

lmtp_mx_session_limit (default:	2)
       The LMTP-specific version of  the  smtp_mx_session_limit	 configuration
       parameter.  See there for details.

       This feature is available in Postfix 2.3	and later.

lmtp_nested_header_checks (default: empty)
       The  LMTP-specific  version of the smtp_nested_header_checks configura-
       tion parameter. See there for details.

       This feature is available in Postfix 2.5	and later.

lmtp_pix_workaround_delay_time (default: 10s)
       The LMTP-specific version of the	smtp_pix_workaround_delay_time config-
       uration parameter.  See there for details.

       This feature is available in Postfix 2.3	and later.

lmtp_pix_workaround_maps (default: empty)
       The LMTP-specific version of the	smtp_pix_workaround_maps configuration
       parameter.  See there for details.

       This feature is available in Postfix 2.4	and later.

lmtp_pix_workaround_threshold_time (default: 500s)
       The LMTP-specific  version  of  the  smtp_pix_workaround_threshold_time
       configuration parameter.	 See there for details.

       This feature is available in Postfix 2.3	and later.

lmtp_pix_workarounds (default: empty)
       The  LMTP-specific version of the smtp_pix_workaround configuration pa-
       rameter.	 See there for details.

       This feature is available in Postfix 2.4	and later.

lmtp_quit_timeout (default: 300s)
       The LMTP	client time limit for sending the QUIT command,	 and  for  re-
       ceiving the server response.

       Time  units:  s (seconds), m (minutes), h (hours), d (days), w (weeks).
       The default time	unit is	s (seconds).

lmtp_quote_rfc821_envelope (default: yes)
       The LMTP-specific version of the	smtp_quote_rfc821_envelope  configura-
       tion parameter.	See there for details.

       This feature is available in Postfix 2.3	and later.

lmtp_randomize_addresses (default: yes)
       The LMTP-specific version of the	smtp_randomize_addresses configuration
       parameter.  See there for details.

       This feature is available in Postfix 2.3	and later.

lmtp_rcpt_timeout (default: 300s)
       The LMTP	client time limit for sending the RCPT TO command, and for re-
       ceiving the server response.

       Time  units:  s (seconds), m (minutes), h (hours), d (days), w (weeks).
       The default time	unit is	s (seconds).

lmtp_reply_filter (default: empty)
       The LMTP-specific version of the	smtp_reply_filter configuration	param-
       eter.  See there	for details.

       This feature is available in Postfix 2.7	and later.

lmtp_rset_timeout (default: 20s)
       The  LMTP  client  time limit for sending the RSET command, and for re-
       ceiving the server response. The	LMTP client sends  RSET	 in  order  to
       finish a	recipient address probe, or to verify that a cached connection
       is still	alive.

       Time units: s (seconds),	m (minutes), h (hours),	d (days),  w  (weeks).
       The default time	unit is	s (seconds).

lmtp_sasl_auth_cache_name (default: empty)
       The  LMTP-specific  version of the smtp_sasl_auth_cache_name configura-
       tion parameter.	See there for details.

       This feature is available in Postfix 2.5	and later.

lmtp_sasl_auth_cache_time (default: 90d)
       The LMTP-specific version of the	 smtp_sasl_auth_cache_time  configura-
       tion parameter.	See there for details.

       This feature is available in Postfix 2.5	and later.

lmtp_sasl_auth_enable (default:	no)
       Enable SASL authentication in the Postfix LMTP client.

lmtp_sasl_auth_soft_bounce (default: yes)
       The  LMTP-specific version of the smtp_sasl_auth_soft_bounce configura-
       tion parameter.	See there for details.

       This feature is available in Postfix 2.5	and later.

lmtp_sasl_mechanism_filter (default: empty)
       The LMTP-specific version of the	smtp_sasl_mechanism_filter  configura-
       tion parameter.	See there for details.

       This feature is available in Postfix 2.3	and later.

lmtp_sasl_password_maps	(default: empty)
       Optional	LMTP client lookup tables with one username:password entry per
       host or domain.	If a remote host or domain  has	 no  username:password
       entry, then the Postfix LMTP client will	not attempt to authenticate to
       the remote host.

lmtp_sasl_path (default: empty)
       Implementation-specific information that	is passed through to the  SASL
       plug-in implementation that is selected with lmtp_sasl_type.  Typically
       this specifies the name of a configuration file or rendezvous point.

       This feature is available in Postfix 2.3	and later.

lmtp_sasl_security_options (default: noplaintext, noanonymous)
       SASL security options; as of Postfix 2.3	the list of available features
       depends	on  the	 SASL  client  implementation  that  is	 selected with
       lmtp_sasl_type.

       The following security features are defined for the cyrus  client  SASL
       implementation:

       noplaintext
	      Disallow authentication methods that use plaintext passwords.

       noactive
	      Disallow	authentication methods that are	vulnerable to non-dic-
	      tionary active attacks.

       nodictionary
	      Disallow authentication methods that are vulnerable  to  passive
	      dictionary attack.

       noanonymous
	      Disallow anonymous logins.

       Example:

       lmtp_sasl_security_options = noplaintext

lmtp_sasl_tls_security_options (default: $lmtp_sasl_security_options)
       The LMTP-specific version of the	smtp_sasl_tls_security_options config-
       uration parameter.  See there for details.

       This feature is available in Postfix 2.3	and later.

lmtp_sasl_tls_verified_security_options	(default:  $lmtp_sasl_tls_security_op-
       tions)
       The  LMTP-specific  version  of the smtp_sasl_tls_verified_security_op-
       tions configuration parameter.  See there for details.

       This feature is available in Postfix 2.3	and later.

lmtp_sasl_type (default: cyrus)
       The SASL	plug-in	type that the Postfix LMTP client should use  for  au-
       thentication.   The  available  types are listed	with the "postconf -A"
       command.

       This feature is available in Postfix 2.3	and later.

lmtp_send_xforward_command (default: no)
       Send an XFORWARD	command	to the LMTP server when	the LMTP  LHLO	server
       response	 announces  XFORWARD support.  This allows an lmtp(8) delivery
       agent, used for content filter message injection, to forward the	 name,
       address,	 protocol  and HELO name of the	original client	to the content
       filter and downstream queuing LMTP server.  Before you change the value
       to  yes,	it is best to make sure	that your content filter supports this
       command.

       This feature is available in Postfix 2.1	and later.

lmtp_sender_dependent_authentication (default: no)
       The LMTP-specific version of  the  smtp_sender_dependent_authentication
       configuration parameter.	 See there for details.

       This feature is available in Postfix 2.3	and later.

lmtp_skip_5xx_greeting (default: yes)
       The  LMTP-specific  version of the smtp_skip_5xx_greeting configuration
       parameter.  See there for details.

       This feature is available in Postfix 2.3	and later.

lmtp_skip_quit_response	(default: no)
       Wait for	the response to	the LMTP QUIT command.

lmtp_starttls_timeout (default:	300s)
       The LMTP-specific version of  the  smtp_starttls_timeout	 configuration
       parameter.  See there for details.

       This feature is available in Postfix 2.3	and later.

lmtp_tcp_port (default:	24)
       The default TCP port that the Postfix LMTP client connects to.

lmtp_tls_CAfile	(default: empty)
       The  LMTP-specific version of the smtp_tls_CAfile configuration parame-
       ter.  See there for details.

       This feature is available in Postfix 2.3	and later.

lmtp_tls_CApath	(default: empty)
       The LMTP-specific version of the	smtp_tls_CApath	configuration  parame-
       ter.  See there for details.

       This feature is available in Postfix 2.3	and later.

lmtp_tls_block_early_mail_reply	(default: empty)
       The  LMTP-specific  version of the smtp_tls_block_early_mail_reply con-
       figuration parameter.  See there	for details.

       This feature is available in Postfix 2.7	and later.

lmtp_tls_cert_file (default: empty)
       The LMTP-specific version of the	smtp_tls_cert_file  configuration  pa-
       rameter.	 See there for details.

       This feature is available in Postfix 2.3	and later.

lmtp_tls_ciphers (default: export)
       The LMTP-specific version of the	smtp_tls_ciphers configuration parame-
       ter. See	there for details.

       This feature is available in Postfix 2.6	and later.

lmtp_tls_dcert_file (default: empty)
       The LMTP-specific version of the	smtp_tls_dcert_file configuration  pa-
       rameter.	 See there for details.

       This feature is available in Postfix 2.3	and later.

lmtp_tls_dkey_file (default: $lmtp_tls_dcert_file)
       The  LMTP-specific  version of the smtp_tls_dkey_file configuration pa-
       rameter.	 See there for details.

       This feature is available in Postfix 2.3	and later.

lmtp_tls_eccert_file (default: empty)
       The LMTP-specific version of the	smtp_tls_eccert_file configuration pa-
       rameter.	 See there for details.

       This  feature  is  available  in	Postfix	2.6 and	later, when Postfix is
       compiled	and linked with	OpenSSL	1.0.0 or later.

lmtp_tls_eckey_file (default: empty)
       The LMTP-specific version of the	smtp_tls_eckey_file configuration  pa-
       rameter.	 See there for details.

       This  feature  is  available  in	Postfix	2.6 and	later, when Postfix is
       compiled	and linked with	OpenSSL	1.0.0 or later.

lmtp_tls_enforce_peername (default: yes)
       The LMTP-specific version of the	 smtp_tls_enforce_peername  configura-
       tion parameter.	See there for details.

       This feature is available in Postfix 2.3	and later.

lmtp_tls_exclude_ciphers (default: empty)
       The LMTP-specific version of the	smtp_tls_exclude_ciphers configuration
       parameter.  See there for details.

       This feature is available in Postfix 2.3	and later.

lmtp_tls_fingerprint_cert_match	(default: empty)
       The LMTP-specific version of the	 smtp_tls_fingerprint_cert_match  con-
       figuration parameter.  See there	for details.

       This feature is available in Postfix 2.5	and later.

lmtp_tls_fingerprint_digest (default: md5)
       The LMTP-specific version of the	smtp_tls_fingerprint_digest configura-
       tion parameter.	See there for details.

       This feature is available in Postfix 2.5	and later.

lmtp_tls_key_file (default: $lmtp_tls_cert_file)
       The LMTP-specific version of the	smtp_tls_key_file configuration	param-
       eter.  See there	for details.

       This feature is available in Postfix 2.3	and later.

lmtp_tls_loglevel (default: 0)
       The LMTP-specific version of the	smtp_tls_loglevel configuration	param-
       eter.  See there	for details.

       This feature is available in Postfix 2.3	and later.

lmtp_tls_mandatory_ciphers (default: empty)
       The LMTP-specific version of the	smtp_tls_mandatory_ciphers  configura-
       tion parameter.	See there for details.

       This feature is available in Postfix 2.3	and later.

lmtp_tls_mandatory_exclude_ciphers (default: empty)
       The  LMTP-specific  version  of	the smtp_tls_mandatory_exclude_ciphers
       configuration parameter.	 See there for details.

       This feature is available in Postfix 2.3	and later.

lmtp_tls_mandatory_protocols (default: !SSLv2)
       The LMTP-specific version of the	smtp_tls_mandatory_protocols  configu-
       ration parameter. See there for details.

       This feature is available in Postfix 2.3	and later.

lmtp_tls_note_starttls_offer (default: no)
       The  LMTP-specific version of the smtp_tls_note_starttls_offer configu-
       ration parameter.  See there for	details.

       This feature is available in Postfix 2.3	and later.

lmtp_tls_per_site (default: empty)
       The LMTP-specific version of the	smtp_tls_per_site configuration	param-
       eter.  See there	for details.

       This feature is available in Postfix 2.3	and later.

lmtp_tls_policy_maps (default: empty)
       The LMTP-specific version of the	smtp_tls_policy_maps configuration pa-
       rameter.	See there for details.

       This feature is available in Postfix 2.3	and later.

lmtp_tls_protocols (default: empty)
       The LMTP-specific version of the	smtp_tls_protocols  configuration  pa-
       rameter.	See there for details.

       This feature is available in Postfix 2.6	and later.

lmtp_tls_scert_verifydepth (default: 9)
       The  LMTP-specific version of the smtp_tls_scert_verifydepth configura-
       tion parameter.	See there for details.

       This feature is available in Postfix 2.3	and later.

lmtp_tls_secure_cert_match (default: nexthop)
       The LMTP-specific version of the	smtp_tls_secure_cert_match  configura-
       tion parameter. See there for details.

       This feature is available in Postfix 2.3	and later.

lmtp_tls_security_level	(default: empty)
       The  LMTP-specific version of the smtp_tls_security_level configuration
       parameter.  See there for details.

       This feature is available in Postfix 2.3	and later.

lmtp_tls_session_cache_database	(default: empty)
       The LMTP-specific version of the	 smtp_tls_session_cache_database  con-
       figuration parameter. See there for details.

       This feature is available in Postfix 2.3	and later.

lmtp_tls_session_cache_timeout (default: 3600s)
       The LMTP-specific version of the	smtp_tls_session_cache_timeout config-
       uration parameter.  See there for details.

       This feature is available in Postfix 2.3	and later.

lmtp_tls_verify_cert_match (default: hostname)
       The LMTP-specific version of the	smtp_tls_verify_cert_match  configura-
       tion parameter. See there for details.

       This feature is available in Postfix 2.3	and later.

lmtp_use_tls (default: no)
       The  LMTP-specific version of the smtp_use_tls configuration parameter.
       See there for details.

       This feature is available in Postfix 2.3	and later.

lmtp_xforward_timeout (default:	300s)
       The LMTP	client time limit for sending the XFORWARD  command,  and  for
       receiving the server response.

       In  case	 of  problems  the client does NOT try the next	address	on the
       mail exchanger list.

       Time units: s (seconds),	m (minutes), h (hours),	d (days),  w  (weeks).
       The default time	unit is	s (seconds).

       This feature is available in Postfix 2.1	and later.

local_command_shell (default: empty)
       Optional	 shell	program	 for local(8) delivery to non-Postfix command.
       By default, non-Postfix commands	are executed  directly;	 commands  are
       given to	given to the default shell (typically, /bin/sh)	only when they
       contain shell meta characters or	shell built-in commands.

       "sendmail's restricted shell" (smrsh) is	what most people will  use  in
       order  to  restrict  what  programs can be run from e.g.	.forward files
       (smrsh is part of the Sendmail distribution).

       Note: when a shell program is specified,	it is invoked  even  when  the
       command contains	no shell built-in commands or meta characters.

       Example:

       local_command_shell = /some/where/smrsh -c
       local_command_shell = /bin/bash -c

local_destination_concurrency_limit (default: 2)
       The  maximal  number of parallel	deliveries via the local mail delivery
       transport  to  the  same	 recipient  (when   "local_destination_recipi-
       ent_limit  =  1")  or  the maximal number of parallel deliveries	to the
       same local domain (when "local_destination_recipient_limit > 1").  This
       limit  is enforced by the queue manager.	The message delivery transport
       name is the first field in the entry in the master.cf file.

       A low limit of 2	is recommended,	just in	case someone has an  expensive
       shell  command  in a .forward file or in	an alias (e.g.,	a mailing list
       manager).  You don't want to run	lots of	those at the same time.

local_destination_recipient_limit (default: 1)
       The maximal number of recipients	per message  delivery  via  the	 local
       mail  delivery  transport. This limit is	enforced by the	queue manager.
       The message delivery transport name is the first	field in the entry  in
       the master.cf file.

       Setting this parameter to a value > 1 changes the meaning of local_des-
       tination_concurrency_limit from concurrency per recipient into  concur-
       rency per domain.

local_header_rewrite_clients (default: permit_inet_interfaces)
       Rewrite	message	header addresses in mail from these clients and	update
       incomplete addresses with the domain name in  $myorigin	or  $mydomain;
       either  don't rewrite message headers from other	clients	at all,	or re-
       write message headers and update	incomplete addresses with  the	domain
       specified in the	remote_header_rewrite_domain parameter.

       See  the	 append_at_myorigin and	append_dot_mydomain parameters for de-
       tails of	how domain names are appended to incomplete addresses.

       Specify a list of zero or more of the following:

       permit_inet_interfaces
	      Append the domain	name in	$myorigin or $mydomain when the	client
	      IP address matches $inet_interfaces. This	is enabled by default.

       permit_mynetworks
	      Append the domain	name in	$myorigin or $mydomain when the	client
	      IP address matches any network  or  network  address  listed  in
	      $mynetworks.  This  setting  will	not prevent remote mail	header
	      address rewriting	when mail from a remote	client is forwarded by
	      a	neighboring system.

       permit_sasl_authenticated
	      Append the domain	name in	$myorigin or $mydomain when the	client
	      is successfully authenticated via	the RFC	4954 (AUTH) protocol.

       permit_tls_clientcerts
	      Append the domain	name in	$myorigin or $mydomain when the	client
	      TLS  certificate	fingerprint  is	 listed	in $relay_clientcerts.
	      The  fingerprint	digest	algorithm  is  configurable  via   the
	      smtpd_tls_fingerprint_digest  parameter (hard-coded as md5 prior
	      to Postfix version 2.5).

       permit_tls_all_clientcerts
	      Append the domain	name in	$myorigin or $mydomain when the	client
	      TLS  certificate is successfully verified, regardless of whether
	      it is listed on the server, and regardless of the	certifying au-
	      thority.

       check_address_map type:table

       type:table
	      Append the domain	name in	$myorigin or $mydomain when the	client
	      IP address matches the specified lookup table.  The  lookup  re-
	      sult  is ignored,	and no subnet lookup is	done. This is suitable
	      for, e.g., pop-before-smtp lookup	tables.

       Examples:

       The Postfix < 2.2 backwards compatible setting: always rewrite  message
       headers,	 and  always  append  my  own  domain to incomplete header ad-
       dresses.

	   local_header_rewrite_clients	= static:all

       The purist (and default)	setting: rewrite headers  only	in  mail  from
       Postfix sendmail	and in SMTP mail from this machine.

	   local_header_rewrite_clients	= permit_inet_interfaces

       The intermediate	setting: rewrite header	addresses and append $myorigin
       or $mydomain information	only with mail from Postfix sendmail, from lo-
       cal clients, or from authorized SMTP clients.

       Note:  this setting will	not prevent remote mail	header address rewrit-
       ing when	mail from a remote client is forwarded by a  neighboring  sys-
       tem.

	   local_header_rewrite_clients	= permit_mynetworks,
	       permit_sasl_authenticated permit_tls_clientcerts
	       check_address_map hash:/etc/postfix/pop-before-smtp

local_recipient_maps (default: proxy:unix:passwd.byname	$alias_maps)
       Lookup tables with all names or addresses of local recipients: a	recip-
       ient address is local when its domain matches $mydestination, $inet_in-
       terfaces	 or $proxy_interfaces.	Specify	@domain	as a wild-card for do-
       mains that do not have a	valid  recipient  list.	  Technically,	tables
       listed  with  $local_recipient_maps are used as lists: Postfix needs to
       know only if a lookup string is found or	not, but it does not  use  the
       result from table lookup.

       If  this	 parameter  is	non-empty (the default), then the Postfix SMTP
       server will reject mail for unknown local users.

       To turn off local recipient checking in the Postfix SMTP	server,	 spec-
       ify "local_recipient_maps =" (i.e. empty).

       The  default setting assumes that you use the default Postfix local de-
       livery agent for	local delivery.	You need to update  the	 local_recipi-
       ent_maps	setting	if:

       o      You redefine the local delivery agent in master.cf.

       o      You redefine the "local_transport" setting in main.cf.

       o      You   use	 the  "luser_relay",  "mailbox_transport",  or	"fall-
	      back_transport" feature of the Postfix local(8) delivery agent.

       Details are described in	the LOCAL_RECIPIENT_README file.

       Beware: if the Postfix SMTP server runs chrooted, you  need  to	access
       the  passwd  file via the proxymap(8) service, in order to overcome ch-
       root access restrictions. The alternative, maintaining a	 copy  of  the
       system password file in the chroot jail is not practical.

       Examples:

       local_recipient_maps =

local_transport	(default: local:$myhostname)
       The  default mail delivery transport and	next-hop destination for final
       delivery	to domains listed with mydestination, and for [ipaddress] des-
       tinations  that	match $inet_interfaces or $proxy_interfaces.  This in-
       formation can be	overruled with the transport(5)	table.

       By default, local mail is delivered to the  transport  called  "local",
       which is	just the name of a service that	is defined the master.cf file.

       Specify	a string of the	form transport:nexthop,	where transport	is the
       name of a mail delivery transport defined in master.cf.	 The  :nexthop
       destination is optional;	its syntax is documented in the	manual page of
       the corresponding delivery agent.

       Beware: if you override the default local delivery agent	then you  need
       to  review  the	LOCAL_RECIPIENT_README	document,  otherwise  the SMTP
       server may reject mail for local	recipients.

luser_relay (default: empty)
       Optional	catch-all destination for unknown local(8) recipients.	By de-
       fault,  mail  for  unknown recipients in	domains	that match $mydestina-
       tion, $inet_interfaces or $proxy_interfaces is returned	as  undeliver-
       able.

       The following $name expansions are done on luser_relay:

       $domain
	      The recipient domain.

       $extension
	      The recipient address extension.

       $home  The recipient's home directory.

       $local The entire recipient address localpart.

       $recipient
	      The full recipient address.

       $recipient_delimiter
	      The system-wide recipient	address	extension delimiter.

       $shell The recipient's login shell.

       $user  The recipient username.

       ${name?value}
	      Expands to value when $name has a	non-empty value.

       ${name:value}
	      Expands to value when $name has an empty value.

       Instead of $name	you can	also specify ${name} or	$(name).

       Note: luser_relay works only for	the Postfix local(8) delivery agent.

       Note:  if  you  use  this feature for accounts not in the UNIX password
       file, then you must specify "local_recipient_maps ="  (i.e.  empty)  in
       the  main.cf  file,  otherwise the Postfix SMTP server will reject mail
       for non-UNIX accounts with "User	unknown	in local recipient table".

       Examples:

       luser_relay = $user@other.host
       luser_relay = $local@other.host
       luser_relay = admin+$local

mail_name (default: Postfix)
       The mail	system name that is displayed in  Received:  headers,  in  the
       SMTP greeting banner, and in bounced mail.

mail_owner (default: postfix)
       The  UNIX  system  account that owns the	Postfix	queue and most Postfix
       daemon processes.  Specify the name of a	user  account  that  does  not
       share  a	group with other accounts and that owns	no other files or pro-
       cesses on the system.  In particular, don't specify nobody  or  daemon.
       PLEASE USE A DEDICATED USER ID AND GROUP	ID.

       When  this  parameter value is changed you need to re-run "postfix set-
       permissions" (with Postfix version 2.0 and earlier: "/etc/postfix/post-
       install set-permissions".

mail_release_date (default: see	postconf -d output)
       The Postfix release date, in "YYYYMMDD" format.

mail_spool_directory (default: see postconf -d output)
       The directory where local(8) UNIX-style mailboxes are kept. The default
       setting depends on the system type. Specify a  name  ending  in	/  for
       maildir-style delivery.

       Note:  maildir  delivery	 is done with the privileges of	the recipient.
       If you use the mail_spool_directory setting for maildir style delivery,
       then  you must create the top-level maildir directory in	advance. Post-
       fix will	not create it.

       Examples:

       mail_spool_directory = /var/mail
       mail_spool_directory = /var/spool/mail

mail_version (default: see postconf -d output)
       The version of the mail system. Stable  releases	 are  named  major.mi-
       nor.patchlevel.	Experimental  releases	also include the release date.
       The version string can be used in, for example, the SMTP	greeting  ban-
       ner.

mailbox_command	(default: empty)
       Optional	 external  command that	the local(8) delivery agent should use
       for mailbox delivery.  The command is run with the user ID and the pri-
       mary group ID privileges	of the recipient.  Exception: command delivery
       for root	executes with $default_privs privileges.  This is not a	 prob-
       lem,  because  1) mail for root should always be	aliased	to a real user
       and 2) don't log	in as root, use	"su" instead.

       The following environment variables are exported	to the command:

       CLIENT_ADDRESS
	      Remote client network address. Available in Postfix version  2.2
	      and later.

       CLIENT_HELO
	      Remote  client EHLO command parameter. Available in Postfix ver-
	      sion 2.2 and later.

       CLIENT_HOSTNAME
	      Remote client hostname. Available	in  Postfix  version  2.2  and
	      later.

       CLIENT_PROTOCOL
	      Remote  client  protocol.	 Available  in Postfix version 2.2 and
	      later.

       DOMAIN The domain part of the recipient address.

       EXTENSION
	      The optional address extension.

       HOME   The recipient home directory.

       LOCAL  The recipient address localpart.

       LOGNAME
	      The recipient's username.

       ORIGINAL_RECIPIENT
	      The entire recipient address, before any	address	 rewriting  or
	      aliasing.

       RECIPIENT
	      The full recipient address.

       SASL_METHOD
	      SASL  authentication  method specified in	the remote client AUTH
	      command. Available in Postfix version 2.2	and later.

       SASL_SENDER
	      SASL sender address specified in the  remote  client  MAIL  FROM
	      command. Available in Postfix version 2.2	and later.

       SASL_USER
	      SASL  username  specified	 in  the  remote  client AUTH command.
	      Available	in Postfix version 2.2 and later.

       SENDER The full sender address.

       SHELL  The recipient's login shell.

       USER   The recipient username.

       Unlike other Postfix configuration parameters, the mailbox_command  pa-
       rameter	is  not	 subjected  to $name substitutions. This is to make it
       easier to specify shell syntax (see example below).

       If you can, avoid shell meta characters because they will force Postfix
       to  run	an  expensive shell process. If	you're delivering via Procmail
       then running a shell won't make a noticeable difference	in  the	 total
       cost.

       Note:  if  you  use the mailbox_command feature to deliver mail system-
       wide, you must set up an	alias that forwards mail for root  to  a  real
       user.

       The  precedence	of  local(8)  delivery	features  from high to low is:
       aliases,	 .forward  files,  mailbox_transport_maps,  mailbox_transport,
       mailbox_command_maps,  mailbox_command, home_mailbox, mail_spool_direc-
       tory, fallback_transport_maps, fallback_transport and luser_relay.

       Examples:

       mailbox_command = /some/where/procmail
       mailbox_command = /some/where/procmail -a "$EXTENSION"
       mailbox_command = /some/where/maildrop -d "$USER"
	       -f "$SENDER" "$EXTENSION"

mailbox_command_maps (default: empty)
       Optional	lookup tables with per-recipient external commands to use  for
       local(8)	mailbox	delivery.  Behavior is as with mailbox_command.

       The  precedence	of  local(8)  delivery	features  from high to low is:
       aliases,	 .forward  files,  mailbox_transport_maps,  mailbox_transport,
       mailbox_command_maps,  mailbox_command, home_mailbox, mail_spool_direc-
       tory, fallback_transport_maps, fallback_transport and luser_relay.

mailbox_delivery_lock (default:	see postconf -d	output)
       How to lock a UNIX-style	local(8) mailbox before	 attempting  delivery.
       For  a  list  of	 available file	locking	methods, use the "postconf -l"
       command.

       This setting is ignored with maildir style delivery, because  such  de-
       liveries	are safe without explicit locks.

       Note:  The  dotlock  method  requires that the recipient	UID or GID has
       write access to the parent directory of the mailbox file.

       Note: the default setting of this parameter is system dependent.

mailbox_size_limit (default: 51200000)
       The maximal size	of any local(8)	individual mailbox or maildir file, or
       zero  (no  limit).   In	fact, this limits the size of any file that is
       written to upon local delivery, including  files	 written  by  external
       commands	that are executed by the local(8) delivery agent.

       This limit must not be smaller than the message size limit.

mailbox_transport (default: empty)
       Optional	 message  delivery  transport that the local(8)	delivery agent
       should use for mailbox delivery to all local recipients,	whether	or not
       they are	found in the UNIX passwd database.

       The  precedence	of  local(8)  delivery	features  from high to low is:
       aliases,	 .forward  files,  mailbox_transport_maps,  mailbox_transport,
       mailbox_command_maps,  mailbox_command, home_mailbox, mail_spool_direc-
       tory, fallback_transport_maps, fallback_transport and luser_relay.

mailbox_transport_maps (default: empty)
       Optional	lookup tables with per-recipient message  delivery  transports
       to use for local(8) mailbox delivery, whether or	not the	recipients are
       found in	the UNIX passwd	database.

       The precedence of local(8) delivery  features  from  high  to  low  is:
       aliases,	 .forward  files,  mailbox_transport_maps,  mailbox_transport,
       mailbox_command_maps, mailbox_command, home_mailbox,  mail_spool_direc-
       tory, fallback_transport_maps, fallback_transport and luser_relay.

       For  safety  reasons, this feature does not allow $number substitutions
       in regular expression maps.

       This feature is available in Postfix 2.3	and later.

mailq_path (default: see postconf -d output)
       Sendmail	 compatibility	feature	 that  specifies  where	 the   Postfix
       mailq(1)	 command  is  installed.  This command can be used to list the
       Postfix mail queue.

manpage_directory (default: see	postconf -d output)
       Where the Postfix manual	pages are installed.

maps_rbl_domains (default: empty)
       Obsolete	feature: use the reject_rbl_client feature instead.

maps_rbl_reject_code (default: 554)
       The numerical Postfix SMTP server response  code	 when  a  remote  SMTP
       client	 request    is	 blocked   by	the   reject_rbl_client,   re-
       ject_rhsbl_client, reject_rhsbl_reverse_client, reject_rhsbl_sender  or
       reject_rhsbl_recipient restriction.

       Do  not	change	this  unless  you have a complete understanding	of RFC
       2821.

masquerade_classes (default: envelope_sender, header_sender, header_recipient)

       What addresses are subject to address masquerading.

       By  default,  address  masquerading  is	limited	to envelope sender ad-
       dresses,	and to header sender and header	recipient addresses.  This al-
       lows  you to use	address	masquerading on	a mail gateway while still be-
       ing able	to forward mail	to users on individual machines.

       Specify	zero  or   more	  of:	envelope_sender,   envelope_recipient,
       header_sender, header_recipient

masquerade_domains (default: empty)
       Optional	list of	domains	whose subdomain	structure will be stripped off
       in email	addresses.

       The list	is processed left to right, and	processing stops at the	 first
       match.  Thus,

	   masquerade_domains =	foo.example.com	example.com

       strips  "user@any.thing.foo.example.com"	to "user@foo.example.com", but
       strips "user@any.thing.else.example.com"	to "user@example.com".

       A domain	name prefixed with ! means do not masquerade  this  domain  or
       its subdomains. Thus,

	   masquerade_domains =	!foo.example.com example.com

       does  not  change  "user@any.thing.foo.example.com"  or "user@foo.exam-
       ple.com", but strips "user@any.thing.else.example.com"  to  "user@exam-
       ple.com".

       Note:  with  Postfix  version  2.2, message header address masquerading
       happens only when message header	address	rewriting is enabled:

       o      The message is received with the Postfix sendmail(1) command,

       o      The message is received from a network client that matches  $lo-
	      cal_header_rewrite_clients,

       o      The   message   is  received  from  the  network,	 and  the  re-
	      mote_header_rewrite_domain  parameter  specifies	 a   non-empty
	      value.

       To   get	  the  behavior	 before	 Postfix  version  2.2,	 specify  "lo-
       cal_header_rewrite_clients = static:all".

       Example:

       masquerade_domains = $mydomain

masquerade_exceptions (default:	empty)
       Optional	list of	user names that	are  not  subjected  to	 address  mas-
       querading, even when their address matches $masquerade_domains.

       By default, address masquerading	makes no exceptions.

       Specify	a  list	 of user names,	"/file/name" or	"type:table" patterns,
       separated by commas and/or whitespace. The  list	 is  matched  left  to
       right,  and the search stops on the first match.	A "/file/name" pattern
       is replaced by its contents; a "type:table"  lookup  table  is  matched
       when  a name matches a lookup key (the lookup result is ignored).  Con-
       tinue long lines	by starting the	next  line  with  whitespace.  Specify
       "!pattern"  to  exclude a name from the list. The form "!/file/name" is
       supported only in Postfix version 2.4 and later.

       Examples:

       masquerade_exceptions = root, mailer-daemon
       masquerade_exceptions = root

master_service_disable (default: empty)
       Selectively disable master(8) listener ports by service type or by ser-
       vice  name  and type.  Specify a	list of	service	types ("inet", "unix",
       "fifo", or "pass") or "name.type" tuples, where	"name"	is  the	 first
       field  of a master.cf entry and "type" is a service type. As with other
       Postfix matchlists, a search stops at the first match.  Specify	"!pat-
       tern"  to  exclude  a  service from the list. By	default, all master(8)
       listener	ports are enabled.

       Note: this feature does not support "/file/name"	or  "type:table"  pat-
       terns,  nor does	it support wildcards such as "*" or "all". This	is in-
       tentional.

       Examples:

       # Turn on all master(8) listener	ports (the default).
       master_service_disable =
       # Turn off only the main	SMTP listener port.
       master_service_disable =	smtp.inet
       # Turn off all TCP/IP listener ports.
       master_service_disable =	inet
       # Turn off all TCP/IP listener ports except "foo".
       master_service_disable =	!foo.inet, inet

       This feature is available in Postfix 2.6	and later.

max_idle (default: 100s)
       The maximum amount of time that an idle Postfix	daemon	process	 waits
       for an incoming connection before terminating voluntarily.  This	param-
       eter is ignored by the Postfix queue manager and	 by  other  long-lived
       Postfix daemon processes.

       Time  units:  s (seconds), m (minutes), h (hours), d (days), w (weeks).
       The default time	unit is	s (seconds).

max_use	(default: 100)
       The maximal number  of  incoming	 connections  that  a  Postfix	daemon
       process will service before terminating voluntarily.  This parameter is
       ignored by the Postfix queue manager and	by  other  long-lived  Postfix
       daemon processes.

maximal_backoff_time (default: 4000s)
       The maximal time	between	attempts to deliver a deferred message.

       This parameter should be	set to a value greater than or equal to	$mini-
       mal_backoff_time. See also $queue_run_delay.

       Time units: s (seconds),	m (minutes), h (hours),	d (days),  w  (weeks).
       The default time	unit is	s (seconds).

maximal_queue_lifetime (default: 5d)
       The maximal time	a message is queued before it is sent back as undeliv-
       erable.

       Time units: s (seconds),	m (minutes), h (hours),	d (days),  w  (weeks).
       The default time	unit is	d (days).

       Specify 0 when mail delivery should be tried only once.

message_reject_characters (default: empty)
       The set of characters that Postfix will reject in message content.  The
       usual C-like escape sequences are recognized: \a	\b \f \n \r \t \v \ddd
       (up to three octal digits) and \\.

       Example:

       message_reject_characters = \0

       This feature is available in Postfix 2.3	and later.

message_size_limit (default: 10240000)
       The maximal size	in bytes of a message, including envelope information.

       Note:  be  careful  when	making changes.	 Excessively small values will
       result in the loss of non-delivery notifications, when a	bounce message
       size exceeds the	local or remote	MTA's message size limit.

message_strip_characters (default: empty)
       The  set	 of  characters	that Postfix will remove from message content.
       The usual C-like	escape sequences are recognized: \a \b \f \n \r	\t  \v
       \ddd (up	to three octal digits) and \\.

       Example:

       message_strip_characters	= \0

       This feature is available in Postfix 2.3	and later.

milter_command_timeout (default: 30s)
       The  time  limit	 for sending an	SMTP command to	a Milter (mail filter)
       application, and	for receiving the response.

       Specify a non-zero time value (an integral value	plus an	optional  one-
       letter suffix that specifies the	time unit).

       Time  units:  s (seconds), m (minutes), h (hours), d (days), w (weeks).
       The default time	unit is	s (seconds).

       This feature is available in Postfix 2.3	and later.

milter_connect_macros (default:	see postconf -d	output)
       The macros that are sent	to Milter  (mail  filter)  applications	 after
       completion  of  an  SMTP	 connection.  See  MILTER_README for a list of
       available macro names and their meanings.

       This feature is available in Postfix 2.3	and later.

milter_connect_timeout (default: 30s)
       The time	limit for connecting to	a Milter  (mail	 filter)  application,
       and for negotiating protocol options.

       Specify	a non-zero time	value (an integral value plus an optional one-
       letter suffix that specifies the	time unit).

       Time units: s (seconds),	m (minutes), h (hours),	d (days),  w  (weeks).
       The default time	unit is	s (seconds).

       This feature is available in Postfix 2.3	and later.

milter_content_timeout (default: 300s)
       The  time  limit	 for sending message content to	a Milter (mail filter)
       application, and	for receiving the response.

       Specify a non-zero time value (an integral value	plus an	optional  one-
       letter suffix that specifies the	time unit).

       Time  units:  s (seconds), m (minutes), h (hours), d (days), w (weeks).
       The default time	unit is	s (seconds).

       This feature is available in Postfix 2.3	and later.

milter_data_macros (default: see postconf -d output)
       The macros that are sent	to version 4 or	higher	Milter	(mail  filter)
       applications  after the SMTP DATA command. See MILTER_README for	a list
       of available macro names	and their meanings.

       This feature is available in Postfix 2.3	and later.

milter_default_action (default:	tempfail)
       The default action when a Milter	(mail filter) application is  unavail-
       able or mis-configured. Specify one of the following:

       accept Proceed as if the	mail filter was	not present.

       reject Reject  all  further  commands  in this session with a permanent
	      status code.

       tempfail
	      Reject all further commands in this  session  with  a  temporary
	      status code.

       quarantine
	      Like  "accept",  but  freeze  the	 message  in the "hold"	queue.
	      Available	with Postfix 2.6 and later.

       This feature is available in Postfix 2.3	and later.

milter_end_of_data_macros (default: see	postconf -d output)
       The macros that are sent	to Milter (mail	filter)	applications after the
       message	end-of-data.  See  MILTER_README for a list of available macro
       names and their meanings.

       This feature is available in Postfix 2.3	and later.

milter_end_of_header_macros (default: see postconf -d output)
       The macros that are sent	to Milter (mail	filter)	applications after the
       end  of	the  message header. See MILTER_README for a list of available
       macro names and their meanings.

       This feature is available in Postfix 2.5	and later.

milter_header_checks (default: empty)
       Optional	lookup tables for content inspection of	message	 headers  that
       are  produced  by Milter	applications.  See the header_checks(5)	manual
       page available actions. Currently, PREPEND is not implemented.

       The following example sends all mail that is marked as SPAM to  a  spam
       handling	machine. Note that matches are case-insensitive	by default.

       /etc/postfix/main.cf:
	   milter_header_checks	= pcre:/etc/postfix/milter_header_checks

       /etc/postfix/milter_header_checks:
	   /^X-SPAM-FLAG:\s+YES/ FILTER	mysmtp:sanitizer.example.com:25

       The milter_header_checks	mechanism could	also be	used for whitelisting.
       For example it could be used to skip heavy content inspection for DKIM-
       signed mail from	known friendly domains.

       This  feature is	available in Postfix 2.7, and as an optional patch for
       Postfix 2.6.

milter_helo_macros (default: see postconf -d output)
       The macros that are sent	to Milter (mail	filter)	applications after the
       SMTP  HELO  or  EHLO command. See MILTER_README for a list of available
       macro names and their meanings.

       This feature is available in Postfix 2.3	and later.

milter_macro_daemon_name (default: $myhostname)
       The {daemon_name} macro value for Milter	 (mail	filter)	 applications.
       See  MILTER_README  for a list of available macro names and their mean-
       ings.

       This feature is available in Postfix 2.3	and later.

milter_macro_v (default: $mail_name $mail_version)
       The {v} macro value for Milter (mail filter)  applications.   See  MIL-
       TER_README for a	list of	available macro	names and their	meanings.

       This feature is available in Postfix 2.3	and later.

milter_mail_macros (default: see postconf -d output)
       The macros that are sent	to Milter (mail	filter)	applications after the
       SMTP MAIL FROM command. See MILTER_README for a list of available macro
       names and their meanings.

       This feature is available in Postfix 2.3	and later.

milter_protocol	(default: 6)
       The  mail  filter protocol version and optional protocol	extensions for
       communication with a Milter application;	prior to Postfix 2.6  the  de-
       fault  protocol is 2. Postfix sends this	version	number during the ini-
       tial protocol handshake.	 It should match the version  number  that  is
       expected	by the mail filter application (or by its Milter library).

       Protocol	versions:

       2      Use  Sendmail  8	mail  filter  protocol version 2 (default with
	      Sendmail version 8.11 .. 8.13 and	Postfix	version	2.3 ..	2.5).

       3      Use Sendmail 8 mail filter protocol version 3.

       4      Use Sendmail 8 mail filter protocol version 4.

       6      Use Sendmail 8 mail filter  protocol  version  6	(default  with
	      Sendmail version 8.14 and	Postfix	version	2.6).

       Protocol	extensions:

       no_header_reply
	      Specify this when	the Milter application will not	reply for each
	      individual message header.

       This feature is available in Postfix 2.3	and later.

milter_rcpt_macros (default: see postconf -d output)
       The macros that are sent	to Milter (mail	filter)	applications after the
       SMTP  RCPT  TO command. See MILTER_README for a list of available macro
       names and their meanings.

       This feature is available in Postfix 2.3	and later.

milter_unknown_command_macros (default:	see postconf -d	output)
       The macros that are sent	to version 3 or	higher	Milter	(mail  filter)
       applications  after  an	unknown	SMTP command.  See MILTER_README for a
       list of available macro names and their meanings.

       This feature is available in Postfix 2.3	and later.

mime_boundary_length_limit (default: 2048)
       The maximal length of MIME multipart boundary strings. The MIME proces-
       sor  is unable to distinguish between boundary strings that do not dif-
       fer in the first	$mime_boundary_length_limit characters.

       This feature is available in Postfix 2.0	and later.

mime_header_checks (default: $header_checks)
       Optional	lookup tables for content inspection of	MIME  related  message
       headers,	as described in	the header_checks(5) manual page.

       This feature is available in Postfix 2.0	and later.

mime_nesting_limit (default: 100)
       The maximal recursion level that	the MIME processor will	handle.	 Post-
       fix refuses mail	that is	nested deeper than the specified limit.

       This feature is available in Postfix 2.0	and later.

minimal_backoff_time (default: 300s)
       The minimal time	between	attempts to deliver a deferred message;	 prior
       to Postfix 2.4 the default value	was 1000s.

       This  parameter also limits the time an unreachable destination is kept
       in the short-term, in-memory, destination status	cache.

       This parameter should be	set greater than or equal to $queue_run_delay.
       See also	$maximal_backoff_time.

       Time  units:  s (seconds), m (minutes), h (hours), d (days), w (weeks).
       The default time	unit is	s (seconds).

multi_instance_directories (default: empty)
       An optional list	 of  non-default  Postfix  configuration  directories;
       these directories belong	to additional Postfix instances	that share the
       Postfix executable files	and documentation with the default Postfix in-
       stance,	and that are started, stopped, etc., together with the default
       Postfix instance.  Specify a list of pathnames separated	 by  comma  or
       whitespace.

       When  $multi_instance_directories is empty, the postfix(1) command runs
       in single-instance mode and operates on a single	Postfix	instance only.
       Otherwise,  the	postfix(1) command runs	in multi-instance mode and in-
       vokes  the  multi-instance  manager  specified	with   the   multi_in-
       stance_wrapper  parameter.  The multi-instance manager in turn executes
       postfix(1) commands for the default instance and	for  all  Postfix  in-
       stances in $multi_instance_directories.

       Currently,  this	 parameter  setting  is	ignored	except for the default
       main.cf file.

       This feature is available in Postfix 2.6	and later.

multi_instance_enable (default:	no)
       Allow this Postfix instance to be started, stopped, etc., by  a	multi-
       instance	 manager.   By	default,  new  instances are created in	a safe
       state that prevents them	from being started inadvertently.  This	param-
       eter is reserved	for the	multi-instance manager.

       This feature is available in Postfix 2.6	and later.

multi_instance_group (default: empty)
       The  optional  instance	group  name  of	this Postfix instance. A group
       identifies closely-related Postfix instances  that  the	multi-instance
       manager	can  start, stop, etc.,	as a unit.  This parameter is reserved
       for the multi-instance manager.

       This feature is available in Postfix 2.6	and later.

multi_instance_name (default: empty)
       The optional instance name of this Postfix instance. This name  becomes
       also the	default	value for the syslog_name parameter.

       This feature is available in Postfix 2.6	and later.

multi_instance_wrapper (default: empty)
       The  pathname  of  a multi-instance manager command that	the postfix(1)
       command invokes when the	multi_instance_directories parameter value  is
       non-empty.  The	pathname  may be followed by initial command arguments
       separated by whitespace;	shell metacharacters such as  quotes  are  not
       supported in this context.

       The  postfix(1) command invokes the manager command with	the postfix(1)
       non-option command arguments on the manager command line, and with  all
       installation configuration parameters exported into the manager command
       process environment. The	manager	command	in turn	invokes	the postfix(1)
       command	for  individual	Postfix	instances as "postfix -c config_direc-
       tory command".

       This feature is available in Postfix 2.6	and later.

multi_recipient_bounce_reject_code (default: 550)
       The numerical Postfix SMTP server response  code	 when  a  remote  SMTP
       client request is blocked by the	reject_multi_recipient_bounce restric-
       tion.

       Do not change this unless you have  a  complete	understanding  of  RFC
       2821.

       This feature is available in Postfix 2.1	and later.

mydestination (default:	$myhostname, localhost.$mydomain, localhost)
       The  list  of  domains that are delivered via the $local_transport mail
       delivery	transport. By default this is the  Postfix  local(8)  delivery
       agent  which  looks  up all recipients in /etc/passwd and /etc/aliases.
       The SMTP	 server	 validates  recipient  addresses  with	$local_recipi-
       ent_maps	and rejects non-existent recipients. See also the local	domain
       class in	the ADDRESS_CLASS_README file.

       The default mydestination value specifies names for the	local  machine
       only.  On a mail	domain gateway,	you should also	include	$mydomain.

       The  $local_transport  delivery	method	is  also selected for mail ad-
       dressed to user@[the.net.work.address] of the mail system (the  IP  ad-
       dresses specified with the inet_interfaces and proxy_interfaces parame-
       ters).

       Warnings:

       o      Do not specify the names of virtual domains - those domains  are
	      specified	elsewhere. See VIRTUAL_README for more information.

       o      Do  not specify the names	of domains that	this machine is	backup
	      MX host for. See STANDARD_CONFIGURATION_README for how to	set up
	      backup MX	hosts.

       o      By  default, the Postfix SMTP server rejects mail	for recipients
	      not listed with the  local_recipient_maps	 parameter.   See  the
	      postconf(5) manual for a description of the local_recipient_maps
	      and unknown_local_recipient_reject_code parameters.

       Specify a list of host or domain	names,	"/file/name"  or  "type:table"
       patterns, separated by commas and/or whitespace.	A "/file/name" pattern
       is replaced by its contents; a "type:table"  lookup  table  is  matched
       when  a name matches a lookup key (the lookup result is ignored).  Con-
       tinue long lines	by starting the	next line with whitespace.

       Examples:

       mydestination = $myhostname, localhost.$mydomain	$mydomain
       mydestination = $myhostname, localhost.$mydomain	www.$mydomain, ftp.$mydomain

mydomain (default: see postconf	-d output)
       The internet domain name	of this	mail system.  The default  is  to  use
       $myhostname  minus  the	first component, or "localdomain" (Postfix 2.3
       and later).  $mydomain is used as a default value for many  other  con-
       figuration parameters.

       Example:

       mydomain	= domain.tld

myhostname (default: see postconf -d output)
       The  internet  hostname	of this	mail system. The default is to use the
       fully-qualified domain name (FQDN) from gethostname(), or  to  use  the
       non-FQDN	 result	 from gethostname() and	append ".$mydomain".  $myhost-
       name is used as a default value for many	 other	configuration  parame-
       ters.

       Example:

       myhostname = host.example.com

mynetworks (default: see postconf -d output)
       The  list  of  "trusted"	 SMTP  clients	that have more privileges than
       "strangers".

       In particular, "trusted"	SMTP clients are allowed to relay mail through
       Postfix.	 See the smtpd_recipient_restrictions parameter	description in
       the postconf(5) manual.

       You can specify the list	of "trusted" network addresses by hand or  you
       can let Postfix do it for you (which is the default).  See the descrip-
       tion of the mynetworks_style parameter for more information.

       If you specify the mynetworks list by hand, Postfix ignores the	mynet-
       works_style setting.

       Specify	a list of network addresses or network/netmask patterns, sepa-
       rated by	commas and/or whitespace. Continue long	lines by starting  the
       next line with whitespace.

       The  netmask specifies the number of bits in the	network	part of	a host
       address.	 You can also specify "/file/name" or  "type:table"  patterns.
       A  "/file/name"	pattern	 is  replaced  by its contents;	a "type:table"
       lookup table is matched when a table entry matches a lookup string (the
       lookup result is	ignored).

       The  list  is  matched left to right, and the search stops on the first
       match.  Specify "!pattern" to exclude an	address	or network block  from
       the  list.  The form "!/file/name" is supported only in Postfix version
       2.4 and later.

       Note: IP	version	6 address information must be specified	inside	[]  in
       the  mynetworks	value,	and  in	files specified	with "/file/name".  IP
       version 6 addresses contain the ":" character, and would	 otherwise  be
       confused	with a "type:table" pattern.

       Examples:

       mynetworks = 127.0.0.0/8	168.100.189.0/28
       mynetworks = !192.168.0.1, 192.168.0.0/28
       mynetworks = 127.0.0.0/8	168.100.189.0/28 [::1]/128 [2001:240:587::]/64
       mynetworks = $config_directory/mynetworks
       mynetworks = hash:/etc/postfix/network_table

mynetworks_style (default: subnet)
       The  method to generate the default value for the mynetworks parameter.
       This is the list	of trusted networks for	relay access control etc.

       o      Specify "mynetworks_style	= host"	when  Postfix  should  "trust"
	      only the local machine.

       o      Specify  "mynetworks_style = subnet" when	Postfix	should "trust"
	      SMTP clients in the same IP subnetworks as  the  local  machine.
	      On  Linux,  this	works correctly	only with interfaces specified
	      with the "ifconfig" command.

       o      Specify "mynetworks_style	= class" when Postfix  should  "trust"
	      SMTP  clients  in	 the same IP class A/B/C networks as the local
	      machine.	Don't do this with a dialup  site  -  it  would	 cause
	      Postfix  to  "trust"  your  entire provider's network.  Instead,
	      specify an explicit mynetworks list by hand, as  described  with
	      the mynetworks configuration parameter.

myorigin (default: $myhostname)
       The domain name that locally-posted mail	appears	to come	from, and that
       locally posted mail is delivered	to. The	default, $myhostname, is  ade-
       quate for small sites.  If you run a domain with	multiple machines, you
       should (1) change this to $mydomain and (2) set up a domain-wide	 alias
       database	that aliases each user to user@that.users.mailhost.

       Example:

       myorigin	= $mydomain

nested_header_checks (default: $header_checks)
       Optional	lookup tables for content inspection of	non-MIME message head-
       ers in attached messages, as described in the  header_checks(5)	manual
       page.

       This feature is available in Postfix 2.0	and later.

newaliases_path	(default: see postconf -d output)
       Sendmail	 compatibility	feature	 that  specifies  the  location	of the
       newaliases(1) command. This command can be used to rebuild the local(8)
       aliases(5) database.

non_fqdn_reject_code (default: 504)
       The  numerical  Postfix SMTP server reply code when a client request is
       rejected	by the	reject_non_fqdn_helo_hostname,	reject_non_fqdn_sender
       or reject_non_fqdn_recipient restriction.

non_smtpd_milters (default: empty)
       A  list of Milter (mail filter) applications for	new mail that does not
       arrive via the Postfix smtpd(8) server. This includes local  submission
       via the sendmail(1) command line, new mail that arrives via the Postfix
       qmqpd(8)	server,	and old	mail that is re-injected into the  queue  with
       "postsuper -r".	See the	MILTER_README document for details.

       This feature is available in Postfix 2.3	and later.

notify_classes (default: resource, software)
       The  list of error classes that are reported to the postmaster. The de-
       fault is	to report only the most	serious	 problems.  The	 paranoid  may
       wish  to	 turn on the policy (UCE and mail relaying) and	protocol error
       (broken mail software) reports.

       NOTE: postmaster	notifications  may  contain  confidential  information
       such  as	 SASL passwords	or message content.  It	is the system adminis-
       trator's	responsibility to treat	such information with care.

       The error classes are:

       bounce (also implies 2bounce)
	      Send the postmaster copies of the	headers	of bounced  mail,  and
	      send transcripts of SMTP sessions	when Postfix rejects mail. The
	      notification  is	sent  to  the  address	specified   with   the
	      bounce_notice_recipient  configuration parameter (default: post-
	      master).

       2bounce
	      Send undeliverable bounced mail to the postmaster. The notifica-
	      tion  is	sent  to  the  address	specified with the 2bounce_no-
	      tice_recipient configuration parameter (default: postmaster).

       delay  Send the postmaster copies of the	headers	of delayed  mail.  The
	      notification is sent to the address specified with the delay_no-
	      tice_recipient configuration parameter (default: postmaster).

       policy Send the postmaster a transcript of  the	SMTP  session  when  a
	      client request was rejected because of (UCE) policy. The notifi-
	      cation is	sent to	 the  address  specified  with	the  error_no-
	      tice_recipient configuration parameter (default: postmaster).

       protocol
	      Send  the	postmaster a transcript	of the SMTP session in case of
	      client or	server protocol	errors.	The notification  is  sent  to
	      the address specified with the error_notice_recipient configura-
	      tion parameter (default: postmaster).

       resource
	      Inform the postmaster of mail  not  delivered  due  to  resource
	      problems.	  The  notification  is	 sent to the address specified
	      with the	error_notice_recipient	configuration  parameter  (de-
	      fault: postmaster).

       software
	      Inform  the  postmaster  of  mail	 not delivered due to software
	      problems.	 The notification is sent  to  the  address  specified
	      with  the	 error_notice_recipient	 configuration	parameter (de-
	      fault: postmaster).

       Examples:

       notify_classes =	bounce,	delay, policy, protocol, resource, software
       notify_classes =	2bounce, resource, software

owner_request_special (default:	yes)
       Give special treatment to owner-listname	and  listname-request  address
       localparts:  don't split	such addresses when the	recipient_delimiter is
       set to "-".  This feature is useful for mailing lists.

parent_domain_matches_subdomains (default: see postconf	-d output)
       What Postfix features match subdomains of  "domain.tld"	automatically,
       instead	of  requiring  an  explicit  ".domain.tld"  pattern.   This is
       planned backwards compatibility:	 eventually, all Postfix features  are
       expected	 to require explicit ".domain.tld" style patterns when you re-
       ally want to match subdomains.

permit_mx_backup_networks (default: empty)
       Restrict	the use	of the permit_mx_backup	SMTP access  feature  to  only
       domains	whose primary MX hosts match the listed	networks.  The parame-
       ter value syntax	is the same as with the	 mynetworks  parameter;	 note,
       however,	that the default value is empty.

pickup_service_name (default: pickup)
       The  name  of  the  pickup(8) service. This service picks up local mail
       submissions from	the Postfix maildrop queue.

       This feature is available in Postfix 2.0	and later.

plaintext_reject_code (default:	450)
       The numerical Postfix SMTP server response code when a request  is  re-
       jected by the reject_plaintext_session restriction.

       This feature is available in Postfix 2.3	and later.

postmulti_control_commands (default: reload flush)
       The  postfix(1)	commands that the postmulti(1) instance	manager	treats
       as "control" commands, that operate on  running	instances.  For	 these
       commands, disabled instances are	skipped.

       This feature is available in Postfix 2.6	and later.

postmulti_start_commands (default: start)
       The  postfix(1)	commands that the postmulti(1) instance	manager	treats
       as  "start"  commands.  For  these  commands,  disabled	instances  are
       "checked"  rather  than	"started", and failure to "start" a member in-
       stance of an instance group will	abort the start-up of later instances.

       This feature is available in Postfix 2.6	and later.

postmulti_stop_commands	(default: see postconf -d output)
       The postfix(1) commands that the	postmulti(1) instance  manager	treats
       as "stop" commands. For these commands, disabled	instances are skipped,
       and enabled instances are processed in reverse order.

       This feature is available in Postfix 2.6	and later.

postscreen_access_list (default: permit_mynetworks)
       Permanent  white/blacklist  for	remote	SMTP  client   IP   addresses.
       postscreen(8) searches this list	immediately after a remote SMTP	client
       connects.  Specify a comma- or whitespace-separated  list  of  commands
       (in  upper  or  lower case) or lookup tables. The search	stops upon the
       first command that fires	for the	client IP address.

	permit_mynetworks
	      Whitelist	the client and terminate the search if the  client  IP
	      address  matches	$mynetworks.  Do not subject the client	to any
	      before/after 220 greeting	tests.	Pass  the  connection  immedi-
	      ately to a Postfix SMTP server process.

	type:table
	      Query the	specified lookup table.	Each table lookup result is an
	      access list, except that access  lists  inside  a	 table	cannot
	      specify type:table entries.
	      To  discourage  the use of hash, btree, etc. tables, there is no
	      support for substring matching like smtpd(8).  Use  CIDR	tables
	      instead.

	permit
	      Whitelist	 the  client  and terminate the	search.	Do not subject
	      the client to any	before/after 220 greeting tests. Pass the con-
	      nection immediately to a Postfix SMTP server process.

	reject
	      Blacklist	 the  client  and  terminate  the  search. Subject the
	      client to	 the  action  configured  with	the  postscreen_black-
	      list_action configuration	parameter.

	dunno All  postscreen(8)  access lists implicitly have this command at
	      the end.
	      When  dunno is executed inside a lookup table, return  from  the
	      lookup table and evaluate	the next command.
	      When   dunno   is	executed outside a lookup table, terminate the
	      search, and subject the client to	 the  configured  before/after
	      220 greeting tests.

       Example:

       /etc/postfix/main.cf:
	   postscreen_access_list = permit_mynetworks,
		 cidr:/etc/postfix/postscreen_access.cidr

       /etc/postfix/postscreen_access.cidr:
	   # Rules are evaluated in the	order as specified.
	   # Blacklist 192.168.* except	192.168.0.1.
	   192.168.0.1	       dunno
	   192.168.0.0/16      reject

       This feature is available in Postfix 2.8.

postscreen_bare_newline_action (default: ignore)
       The  action  that  postscreen(8)	takes when an SMTP client sends	a bare
       newline character, that is, a newline not preceded by carriage  return.
       Specify one of the following:

       ignore Ignore  the failure of this test.	Allow other tests to complete.
	      Do not repeat this test before some the result from  some	 other
	      test  expires.  This option is useful for	testing	and collecting
	      statistics without blocking mail permanently.

       enforce
	      Allow other tests	to complete. Reject attempts to	 deliver  mail
	      with  a 550 SMTP reply, and log the helo/sender/recipient	infor-
	      mation.  Repeat this test	the next time the client connects.

       drop   Drop the connection immediately with a 521  SMTP	reply.	Repeat
	      this test	the next time the client connects.

       This feature is available in Postfix 2.8.

postscreen_bare_newline_enable (default: no)
       Enable  "bare newline" SMTP protocol tests in the postscreen(8) server.
       These tests are expensive: a client must	disconnect after it passes the
       test, before it can talk	to a real Postfix SMTP server.

       This feature is available in Postfix 2.8.

postscreen_bare_newline_ttl (default: 30d)
       The  amount  of time that postscreen(8) will use	the result from	a suc-
       cessful "bare newline" SMTP protocol test. During this time, the	client
       IP  address  is	excluded from this test. The default is	long because a
       client must disconnect after it passes the test,	before it can talk  to
       a real Postfix SMTP server.

       Specify	a non-zero time	value (an integral value plus an optional one-
       letter suffix that specifies the	time unit).  Time units: s  (seconds),
       m (minutes), h (hours), d (days), w (weeks).

       This feature is available in Postfix 2.8.

postscreen_blacklist_action (default: ignore)
       The  action that	postscreen(8) takes when an SMTP client	is permanently
       blacklisted with	the postscreen_access_list parameter.  Specify one  of
       the following:

       ignore (default)
	      Ignore  this result. Allow other tests to	complete.  Repeat this
	      test the next time the client connects.  This option  is	useful
	      for testing and collecting statistics without blocking mail.

       enforce
	      Allow  other  tests to complete. Reject attempts to deliver mail
	      with a 550 SMTP reply, and log the helo/sender/recipient	infor-
	      mation.  Repeat this test	the next time the client connects.

       drop   Drop  the	 connection  immediately with a	521 SMTP reply.	Repeat
	      this test	the next time the client connects.

       This feature is available in Postfix 2.8.

postscreen_cache_cleanup_interval (default: 12h)
       The amount of time between postscreen(8)	 cache	cleanup	 runs.	 Cache
       cleanup	increases  the load on the cache database and should therefore
       not be run frequently. This feature requires that  the  cache  database
       supports	 the "delete" and "sequence" operators.	 Specify a zero	inter-
       val to disable cache cleanup.

       After each cache	cleanup	run, the postscreen(8) daemon logs the	number
       of  entries  that were retained and dropped. A cleanup run is logged as
       "partial" when the daemon  terminates  early  after  "postfix  reload",
       "postfix	stop", or no requests for $max_idle seconds.

       Time units: s (seconds),	m (minutes), h (hours),	d (days), w (weeks).

       This feature is available in Postfix 2.8.

postscreen_cache_map (default: btree:$data_directory/postscreen_cache)
       Persistent storage for the postscreen(8)	server decisions.

       This feature is available in Postfix 2.8.

postscreen_cache_retention_time	(default: 7d)
       The  amount  of time that postscreen(8) will cache an expired temporary
       whitelist entry before it is removed. This prevents clients from	 being
       logged  as "NEW"	just because their cache entry expired an hour ago. It
       also prevents the cache from filling up with clients that  passed  some
       deep protocol test once and never came back.

       Time units: s (seconds),	m (minutes), h (hours),	d (days), w (weeks).

       This feature is available in Postfix 2.8.

postscreen_client_connection_count_limit    (default:	 $smtpd_client_connec-
       tion_count_limit)
       How many	simultaneous connections any client is allowed	to  have  with
       the  postscreen(8)  daemon.  By default,	this limit is the same as with
       the Postfix SMTP	server.	Note that the triage process can take  several
       seconds,	 with  the time	spent in postscreen_greet_wait delay, and with
       the time	spent talking to the postscreen(8) built-in dummy SMTP	proto-
       col engine.

       This feature is available in Postfix 2.8.

postscreen_command_count_limit (default: 20)
       The  limit  on  the  total  number  of  commands	 per  SMTP session for
       postscreen(8)'s built-in	SMTP protocol engine.  This SMTP engine	defers
       or  rejects all attempts	to deliver mail, therefore there is no need to
       enforce separate	limits on the number of	junk commands and  error  com-
       mands.

       This feature is available in Postfix 2.8.

postscreen_command_filter (default: $smtpd_command_filter)
       A  mechanism  to	 transform  commands  from  remote  SMTP clients.  See
       smtpd_command_filter for	further	details.

       This feature is available in Postfix 2.8	and later.

postscreen_command_time_limit (default:	${stress?10}${stress:300}s)
       The time	limit to read an  entire  command  line	 with  postscreen(8)'s
       built-in	SMTP protocol engine.

       This feature is available in Postfix 2.8.

postscreen_disable_vrfy_command	(default: $disable_vrfy_command)
       Disable	the  SMTP  VRFY	command	in the postscreen(8) daemon.  See dis-
       able_vrfy_command for details.

       This feature is available in Postfix 2.8.

postscreen_discard_ehlo_keyword_address_maps	   (default:	   $smtpd_dis-
       card_ehlo_keyword_address_maps)
       Lookup tables, indexed by the remote SMTP client	address, with case in-
       sensitive lists of EHLO keywords	 (pipelining,  starttls,  auth,	 etc.)
       that  the  postscreen(8)	server will not	send in	the EHLO response to a
       remote SMTP client. See smtpd_discard_ehlo_keywords for	details.   The
       table is	not searched by	hostname for robustness	reasons.

       This feature is available in Postfix 2.8	and later.

postscreen_discard_ehlo_keywords (default: $smtpd_discard_ehlo_keywords)
       A  case	insensitive list of EHLO keywords (pipelining, starttls, auth,
       etc.) that the postscreen(8) server will	not send in the	EHLO  response
       to a remote SMTP	client.	See smtpd_discard_ehlo_keywords	for details.

       This feature is available in Postfix 2.8	and later.

postscreen_dnsbl_action	(default: ignore)
       The  action  that  postscreen(8)	 takes	when an	SMTP client's combined
       DNSBL score is equal to or greater than a threshold  (as	 defined  with
       the  postscreen_dnsbl_sites and postscreen_dnsbl_threshold parameters).
       Specify one of the following:

       ignore (default)
	      Ignore the failure of this test. Allow other tests to  complete.
	      Repeat this test the next	time the client	connects.  This	option
	      is useful	for testing and	collecting statistics without blocking
	      mail.

       enforce
	      Allow  other  tests to complete. Reject attempts to deliver mail
	      with a 550 SMTP reply, and log the helo/sender/recipient	infor-
	      mation.  Repeat this test	the next time the client connects.

       drop   Drop  the	 connection  immediately with a	521 SMTP reply.	Repeat
	      this test	the next time the client connects.

       This feature is available in Postfix 2.8.

postscreen_dnsbl_reply_map (default: empty)
       A mapping from actual DNSBL domain name which includes a	 secret	 pass-
       word,  to the DNSBL domain name that postscreen will reply with when it
       rejects mail.  When no mapping is found,	the actual DNSBL  domain  will
       be used.

       For maximal stability it	is best	to use a file that is read into	memory
       such as pcre:, regexp: or texthash: (texthash: is similar to hash:, ex-
       cept a) there is	no need	to run postmap(1) before the file can be used,
       and b) texthash:	does not detect	changes	after the file is read).

       Example:

       /etc/postfix/main.cf:
	   postscreen_dnsbl_reply_map =	texthash:/etc/postfix/dnsbl_reply

       /etc/postfix/dnsbl_reply:
	  secret.zen.spamhaus.org    zen.spamhaus.org

       This feature is available in Postfix 2.8.

postscreen_dnsbl_sites (default: empty)
       Optional	list of	DNS white/blacklist domains, filters and  weight  fac-
       tors.  When  the	 list  is  non-empty, the dnsblog(8) daemon will query
       these domains with  the	IP  addresses  of  remote  SMTP	 clients,  and
       postscreen(8)  will  update an SMTP client's DNSBL score	with each non-
       error reply.

       Caution:	when postscreen	rejects	mail, it replies with the DNSBL	domain
       name. Use the postscreen_dnsbl_reply_map	feature	to hide	"password" in-
       formation in DNSBL domain names.

       When a client's score is	equal to or greater than the threshold	speci-
       fied  with  postscreen_dnsbl_threshold, postscreen(8) can drop the con-
       nection with the	SMTP client.

       Specify a list of domain=filter*weight entries, separated by  comma  or
       whitespace.

       o      When  no "=filter" is specified, postscreen(8) will use any non-
	      error DNSBL reply.  Otherwise,  postscreen(8)  uses  only	 DNSBL
	      replies  that match the filter. The filter has the form d.d.d.d,
	      where each d is a	number,	or a pattern inside []	that  contains
	      one or more ";"-separated	numbers	or number..number ranges.

       o      When  no	"*weight"  is  specified, postscreen(8)	increments the
	      SMTP client's DNSBL score	by 1.  Otherwise, the weight  must  be
	      an  integral number, and postscreen(8) adds the specified	weight
	      to the SMTP client's DNSBL score.	 Specify a negative number for
	      whitelisting.

       o      When  one	 postscreen_dnsbl_sites	 entry produces	multiple DNSBL
	      responses, postscreen(8) applies the weight at most once.

       Examples:

       To use example.com as a high-confidence blocklist, and  to  block  mail
       with example.net	and example.org	only when both agree:

       postscreen_dnsbl_threshold = 2
       postscreen_dnsbl_sites =	example.com*2, example.net, example.org

       To filter only DNSBL replies containing 127.0.0.4:

       postscreen_dnsbl_sites =	example.com=127.0.0.4

       This feature is available in Postfix 2.8.

postscreen_dnsbl_threshold (default: 1)
       The  inclusive  lower  bound  for blocking an SMTP client, based	on its
       combined	DNSBL score as defined with the	postscreen_dnsbl_sites parame-
       ter.

       This feature is available in Postfix 2.8.

postscreen_dnsbl_ttl (default: 1h)
       The  amount  of time that postscreen(8) will use	the result from	a suc-
       cessful DNS blocklist test. During this time, the client	IP address  is
       excluded	 from  this  test.  The	default	is relatively short, because a
       good client can immediately talk	to a real Postfix SMTP server.

       Specify a non-zero time value (an integral value	plus an	optional  one-
       letter  suffix that specifies the time unit).  Time units: s (seconds),
       m (minutes), h (hours), d (days), w (weeks).

       This feature is available in Postfix 2.8.

postscreen_enforce_tls (default: $smtpd_enforce_tls)
       Mandatory TLS: announce STARTTLS	support	to SMTP	clients,  and  require
       that  clients use TLS encryption.  See smtpd_postscreen_enforce_tls for
       details.

       This feature is available in Postfix 2.8	and  later.   Preferably,  use
       postscreen_tls_security_level instead.

postscreen_expansion_filter (default: see postconf -d output)
       List  of	 characters that are permitted in postscreen_reject_footer at-
       tribute expansions.  See	smtpd_expansion_filter for further details.

       This feature is available in Postfix 2.8	and later.

postscreen_forbidden_commands (default:	$smtpd_forbidden_commands)
       List of commands	that the postscreen(8) server considers	 in  violation
       of  the	SMTP  protocol.	 See  smtpd_forbidden_commands for syntax, and
       postscreen_non_smtp_command_action for possible actions.

       This feature is available in Postfix 2.8.

postscreen_greet_action	(default: ignore)
       The action that postscreen(8) takes when	an SMTP	client	speaks	before
       its  turn  within the time specified with the postscreen_greet_wait pa-
       rameter.	 Specify one of	the following:

       ignore (default)
	      Ignore the failure of this test. Allow other tests to  complete.
	      Repeat this test the next	time the client	connects.  This	option
	      is useful	for testing and	collecting statistics without blocking
	      mail.

       enforce
	      Allow  other  tests to complete. Reject attempts to deliver mail
	      with a 550 SMTP reply, and log the helo/sender/recipient	infor-
	      mation.  Repeat this test	the next time the client connects.

       drop   Drop  the	 connection  immediately with a	521 SMTP reply.	Repeat
	      this test	the next time the client connects.

       In either case, postscreen(8) will not whitelist	the SMTP client	IP ad-
       dress.

       This feature is available in Postfix 2.8.

postscreen_greet_banner	(default: $smtpd_banner)
       The   text   in	 the   optional	 "220-text..."	server	response  that
       postscreen(8) sends ahead  of  the  real	 Postfix  SMTP	server's  "220
       text..."	 response,  in	an attempt to confuse bad SMTP clients so that
       they speak before their turn (pre-greet).  Specify an  empty  value  to
       disable this feature.

       This feature is available in Postfix 2.8.

postscreen_greet_ttl (default: 1d)
       The  amount  of time that postscreen(8) will use	the result from	a suc-
       cessful PREGREET	test. During this time,	the client IP address  is  ex-
       cluded  from this test. The default is relatively short,	because	a good
       client can immediately talk to a	real Postfix SMTP server.

       Specify a non-zero time value (an integral value	plus an	optional  one-
       letter  suffix that specifies the time unit).  Time units: s (seconds),
       m (minutes), h (hours), d (days), w (weeks).

       This feature is available in Postfix 2.8.

postscreen_greet_wait (default:	${stress?2}${stress:6}s)
       The amount of time that postscreen(8) will wait for an SMTP  client  to
       send a command before its turn, and for DNS blocklist lookup results to
       arrive (default:	up to 2	seconds	under stress, up to 6  seconds	other-
       wise).

       Specify	a non-zero time	value (an integral value plus an optional one-
       letter suffix that specifies the	time unit).

       Time units: s (seconds),	m (minutes), h (hours),	d (days), w (weeks).

       This feature is available in Postfix 2.8.

postscreen_helo_required (default: $smtpd_helo_required)
       Require that a remote SMTP client sends HELO or EHLO before  commencing
       a MAIL transaction.

       This feature is available in Postfix 2.8.

postscreen_non_smtp_command_action (default: drop)
       The  action that	postscreen(8) takes when an SMTP client	sends non-SMTP
       commands	as specified with the postscreen_forbidden_commands parameter.
       Specify one of the following:

       ignore Ignore  the failure of this test.	Allow other tests to complete.
	      Do not repeat this test before some the result from  some	 other
	      test  expires.  This option is useful for	testing	and collecting
	      statistics without blocking mail permanently.

       enforce
	      Allow other tests	to complete. Reject attempts to	 deliver  mail
	      with  a 550 SMTP reply, and log the helo/sender/recipient	infor-
	      mation.  Repeat this test	the next time the client connects.

       drop   Drop the connection immediately with a 521  SMTP	reply.	Repeat
	      this  test the next time the client connects. This action	is the
	      same as with the Postfix SMTP server's  smtpd_forbidden_commands
	      feature.

       This feature is available in Postfix 2.8.

postscreen_non_smtp_command_enable (default: no)
       Enable  "non-SMTP  command"  tests  in  the postscreen(8) server. These
       tests are expensive: a client must disconnect after it passes the test,
       before it can talk to a real Postfix SMTP server.

       This feature is available in Postfix 2.8.

postscreen_non_smtp_command_ttl	(default: 30d)
       The  amount  of time that postscreen(8) will use	the result from	a suc-
       cessful "non_smtp_command" SMTP protocol	test. During  this  time,  the
       client  IP  address is excluded from this test. The default is long be-
       cause a client must disconnect after it passes the test,	before it  can
       talk to a real Postfix SMTP server.

       Specify	a non-zero time	value (an integral value plus an optional one-
       letter suffix that specifies the	time unit).  Time units: s  (seconds),
       m (minutes), h (hours), d (days), w (weeks).

       This feature is available in Postfix 2.8.

postscreen_pipelining_action (default: enforce)
       The  action that	postscreen(8) takes when an SMTP client	sends multiple
       commands	instead	of sending one command and waiting for the  server  to
       respond.	 Specify one of	the following:

       ignore Ignore  the failure of this test.	Allow other tests to complete.
	      Do not repeat this test before some the result from  some	 other
	      test  expires.  This option is useful for	testing	and collecting
	      statistics without blocking mail permanently.

       enforce
	      Allow other tests	to complete. Reject attempts to	 deliver  mail
	      with  a 550 SMTP reply, and log the helo/sender/recipient	infor-
	      mation.  Repeat this test	the next time the client connects.

       drop   Drop the connection immediately with a 521  SMTP	reply.	Repeat
	      this test	the next time the client connects.

       This feature is available in Postfix 2.8.

postscreen_pipelining_enable (default: no)
       Enable  "pipelining"  SMTP  protocol tests in the postscreen(8) server.
       These tests are expensive: a  good  client  must	 disconnect  after  it
       passes the test,	before it can talk to a	real Postfix SMTP server.

       This feature is available in Postfix 2.8.

postscreen_pipelining_ttl (default: 30d)
       The  amount  of time that postscreen(8) will use	the result from	a suc-
       cessful "pipelining" SMTP protocol test.	During this time,  the	client
       IP  address  is	excluded from this test. The default is	long because a
       good client must	disconnect after it passes the	test,  before  it  can
       talk to a real Postfix SMTP server.

       Specify	a non-zero time	value (an integral value plus an optional one-
       letter suffix that specifies the	time unit).  Time units: s  (seconds),
       m (minutes), h (hours), d (days), w (weeks).

       This feature is available in Postfix 2.8.

postscreen_post_queue_limit (default: $default_process_limit)
       The  number of clients that can be waiting for service from a real SMTP
       server process. When this queue is full,	all clients will receive a 421
       reponse.

       This feature is available in Postfix 2.8.

postscreen_pre_queue_limit (default: $default_process_limit)
       The  number  of non-whitelisted clients that can	be waiting for a deci-
       sion whether they will receive service from a real SMTP server process.
       When this queue is full,	all non-whitelisted clients will receive a 421
       reponse.

       This feature is available in Postfix 2.8.

postscreen_reject_footer (default: $smtpd_reject_footer)
       Optional	information that is appended after a 4XX  or  5XX  server  re-
       sponse. See smtpd_reject_footer for further details.

       This feature is available in Postfix 2.8	and later.

postscreen_tls_security_level (default:	$smtpd_tls_security_level)
       The  SMTP  TLS security level for the postscreen(8) server; when	a non-
       empty value  is	specified,  this  overrides  the  obsolete  parameters
       postscreen_use_tls   and	 postscreen_enforce_tls.  See  smtpd_tls_secu-
       rity_level for details.

       This feature is available in Postfix 2.8	and later.

postscreen_use_tls (default: $smtpd_use_tls)
       Opportunistic TLS: announce STARTTLS support to SMTP  clients,  but  do
       not require that	clients	use TLS	encryption.

       This  feature  is  available in Postfix 2.8 and later.  Preferably, use
       postscreen_tls_security_level instead.

postscreen_watchdog_timeout (default: 10s)
       How much	time a postscreen(8) process may take to respond  to  an  SMTP
       client  command or to perform a cache operation before it is terminated
       by a built-in watchdog timer.  This is a	safety mechanism that prevents
       postscreen(8)  from becoming non-responsive due to a bug	in Postfix it-
       self or in system software.  To	avoid  false  alarms  and  unnecessary
       cache corruption	this limit cannot be set under 10s.

       Specify	a non-zero time	value (an integral value plus an optional one-
       letter suffix that specifies the	time unit).  Time units: s  (seconds),
       m (minutes), h (hours), d (days), w (weeks).

       This feature is available in Postfix 2.8.

prepend_delivered_header (default: command, file, forward)
       The message delivery contexts where the Postfix local(8)	delivery agent
       prepends	a Delivered-To:	 message header	with the address that the mail
       was  delivered  to. This	information is used for	mail delivery loop de-
       tection.

       By default, the Postfix local delivery agent prepends  a	 Delivered-To:
       header  when  forwarding	mail and when delivering to file (mailbox) and
       command.	Turning	off the	Delivered-To: header when forwarding  mail  is
       not recommended.

       Specify zero or more of forward,	file, or command.

       Example:

       prepend_delivered_header	= forward

process_id (read-only)
       The process ID of a Postfix command or daemon process.

process_id_directory (default: pid)
       The  location  of Postfix PID files relative to $queue_directory.  This
       is a read-only parameter.

process_name (read-only)
       The process name	of a Postfix command or	daemon process.

propagate_unmatched_extensions (default: canonical, virtual)
       What address lookup tables copy an address extension  from  the	lookup
       key to the lookup result.

       For   example,	with  a	 virtual(5)  mapping  of  "joe@example.com  =_
       joe.user@example.net", the address "joe+foo@example.com"	would  rewrite
       to "joe.user+foo@example.net".

       Specify	zero or	more of	canonical, virtual, alias, forward, include or
       generic.	These cause address extension propagation  with	 canonical(5),
       virtual(5),  and	 aliases(5) maps, with local(8)	.forward and :include:
       file lookups, and with smtp(8) generic maps, respectively.

       Note: enabling this feature for types other than	canonical and  virtual
       is  likely to cause problems when mail is forwarded to other sites, es-
       pecially	with mail that is sent to a mailing list exploder address.

       Examples:

       propagate_unmatched_extensions =	canonical, virtual, alias,
	       forward,	include
       propagate_unmatched_extensions =	canonical, virtual

proxy_interfaces (default: empty)
       The network interface addresses that this mail system receives mail  on
       by way of a proxy or network address translation	unit.

       This feature is available in Postfix 2.0	and later.

       You must	specify	your "outside" proxy/NAT addresses when	your system is
       a backup	MX host	for other domains, otherwise mail delivery loops  will
       happen when the primary MX host is down.

       Example:

       proxy_interfaces	= 1.2.3.4

proxy_read_maps	(default: see postconf -d output)
       The  lookup tables that the proxymap(8) server is allowed to access for
       the read-only service.  Table references	that don't begin  with	proxy:
       are ignored.

       This feature is available in Postfix 2.0	and later.

proxy_write_maps (default: see postconf	-d output)
       The  lookup tables that the proxymap(8) server is allowed to access for
       the read-write service. Postfix-owned local database  files  should  be
       stored  under  the Postfix-owned	data_directory.	 Table references that
       don't begin with	proxy: are ignored.

       This feature is available in Postfix 2.5	and later.

proxymap_service_name (default:	proxymap)
       The name	of the proxymap	read-only table	lookup service.	 This  service
       is normally implemented by the proxymap(8) daemon.

       This feature is available in Postfix 2.6	and later.

proxywrite_service_name	(default: proxywrite)
       The  name of the	proxywrite read-write table lookup service.  This ser-
       vice is normally	implemented by the proxymap(8) daemon.

       This feature is available in Postfix 2.6	and later.

qmgr_clog_warn_time (default: 300s)
       The minimal delay between warnings that a specific destination is clog-
       ging up the Postfix active queue. Specify 0 to disable.

       This feature is enabled with the	helpful_warnings parameter.

       This feature is available in Postfix 2.0	and later.

qmgr_daemon_timeout (default: 1000s)
       How  much time a	Postfix	queue manager process may take to handle a re-
       quest before it is terminated by	a built-in watchdog timer.

       Time units: s (seconds),	m (minutes), h (hours),	d (days),  w  (weeks).
       The default time	unit is	s (seconds).

       This feature is available in Postfix 2.8	and later.

qmgr_fudge_factor (default: 100)
       Obsolete	feature: the percentage	of delivery resources that a busy mail
       system will use up for delivery of a large mailing  list	message.

       This feature exists only	in the oqmgr(8)	old queue manager. The current
       queue manager solves the	problem	in a better way.

qmgr_ipc_timeout (default: 60s)
       The  time  limit	 for  the queue	manager	to send	or receive information
       over an internal	communication channel.	The purpose is to break	out of
       deadlock	 situations. If	the time limit is exceeded the software	either
       retries or aborts the operation.

       Time units: s (seconds),	m (minutes), h (hours),	d (days),  w  (weeks).
       The default time	unit is	s (seconds).

       This feature is available in Postfix 2.8	and later.

qmgr_message_active_limit (default: 20000)
       The maximal number of messages in the active queue.

qmgr_message_recipient_limit (default: 20000)
       The  maximal  number  of	recipients held	in memory by the Postfix queue
       manager,	and the	maximal	size of	the size of the	short-term,  in-memory
       "dead" destination status cache.

qmgr_message_recipient_minimum (default: 10)
       The  minimal number of in-memory	recipients for any message. This takes
       priority	over any other in-memory recipient limits  (i.e.,  the	global
       qmgr_message_recipient_limit and	the per	transport _recipient_limit) if
       necessary. The minimum value allowed for	this parameter is 1.

qmqpd_authorized_clients (default: empty)
       What clients are	allowed	to connect to the QMQP server port.

       By default, no client is	allowed	to use the service.  This  is  because
       the QMQP	server will relay mail to any destination.

       Specify	a  list	 of  client  patterns. A list pattern specifies	a host
       name, a domain name, an internet	address, or  a	network/mask  pattern,
       where  the mask specifies the number of bits in the network part.  When
       a pattern specifies a file name,	its contents are substituted  for  the
       file  name; when	a pattern is a "type:table" table specification, table
       lookup is used instead.

       Patterns	are separated by whitespace and/or commas. In order to reverse
       the  result,  precede a pattern with an exclamation point (!). The form
       "!/file/name" is	supported only in Postfix version 2.4 and later.

       Example:

       qmqpd_authorized_clients	= !192.168.0.1,	192.168.0.0/24

qmqpd_client_port_logging (default: no)
       Enable logging of the remote QMQP client	port in	addition to the	 host-
       name and	IP address. The	logging	format is "host[address]:port".

       This feature is available in Postfix 2.5	and later.

qmqpd_error_delay (default: 1s)
       How  long the QMQP server will pause before sending a negative reply to
       the client. The purpose is to slow down confused	or malicious clients.

       Time units: s (seconds),	m (minutes), h (hours),	d (days),  w  (weeks).
       The default time	unit is	s (seconds).

qmqpd_timeout (default:	300s)
       The  time  limit	for sending or receiving information over the network.
       If a read or write operation blocks for more than  $qmqpd_timeout  sec-
       onds the	QMQP server gives up and disconnects.

       Time  units:  s (seconds), m (minutes), h (hours), d (days), w (weeks).
       The default time	unit is	s (seconds).

queue_directory	(default: see postconf -d output)
       The location of the Postfix top-level queue directory. This is the root
       directory of Postfix daemon processes that run chrooted.

queue_file_attribute_count_limit (default: 100)
       The  maximal  number of (name=value) attributes that may	be stored in a
       Postfix queue file. The limit is	enforced by the	cleanup(8) server.

       This feature is available in Postfix 2.0	and later.

queue_minfree (default:	0)
       The minimal amount of free space	in bytes in the	queue file system that
       is  needed  to receive mail.  This is currently used by the SMTP	server
       to decide if it will accept any mail at all.

       By default, the Postfix SMTP server rejects MAIL	FROM commands when the
       amount of free space is less than 1.5*$message_size_limit (Postfix ver-
       sion 2.1	and later).  To	specify	a higher  minimum  free	 space	limit,
       specify a queue_minfree value that is at	least 1.5*$message_size_limit.

       With  Postfix  versions	2.0 and	earlier, a queue_minfree value of zero
       means there is no minimum required amount of free space.

queue_run_delay	(default: 300s)
       The time	between	deferred queue scans by	the queue  manager;  prior  to
       Postfix 2.4 the default value was 1000s.

       This  parameter	should	be  set	 less  than or equal to	$minimal_back-
       off_time. See also $maximal_backoff_time.

       Time units: s (seconds),	m (minutes), h (hours),	d (days),  w  (weeks).
       The default time	unit is	s (seconds).

queue_service_name (default: qmgr)
       The name	of the qmgr(8) service.	This service manages the Postfix queue
       and schedules delivery requests.

       This feature is available in Postfix 2.0	and later.

rbl_reply_maps (default: empty)
       Optional	lookup tables with RBL response	templates. The tables are  in-
       dexed by	the RBL	domain name. By	default, Postfix uses the default tem-
       plate as	specified with the default_rbl_reply configuration  parameter.
       See there for a discussion of the syntax	of RBL reply templates.

       This feature is available in Postfix 2.0	and later.

readme_directory (default: see postconf	-d output)
       The  location  of Postfix README	files that describe how	to build, con-
       figure or operate a specific Postfix subsystem or feature.

receive_override_options (default: empty)
       Enable or disable recipient validation, built-in	content	filtering,  or
       address	mapping.  Typically,  these are	specified in master.cf as com-
       mand-line arguments for the smtpd(8), qmqpd(8) or pickup(8) daemons.

       Specify zero or more of the following options.	The  options  override
       main.cf	settings  and are either implemented by	smtpd(8), qmqpd(8), or
       pickup(8) themselves, or	they are forwarded to the cleanup server.

       no_unknown_recipient_checks
	      Do not try to reject  unknown  recipients	 (SMTP	server	only).
	      This is typically	specified AFTER	an external content filter.

       no_address_mappings
	      Disable  canonical address mapping, virtual alias	map expansion,
	      address masquerading, and	automatic BCC (blind carbon-copy)  re-
	      cipients.	This is	typically specified BEFORE an external content
	      filter.

       no_header_body_checks
	      Disable header/body_checks. This is typically specified AFTER an
	      external content filter.

       no_milters
	      Disable  Milter  (mail  filter)  applications. This is typically
	      specified	AFTER an external content filter.

       Note: when the "BEFORE content filter" receive_override_options setting
       is  specified  in  the main.cf file, specify the	"AFTER content filter"
       receive_override_options	setting	in master.cf (and vice versa).

       Examples:

       receive_override_options	=
	   no_unknown_recipient_checks,	no_header_body_checks
       receive_override_options	= no_address_mappings

       This feature is available in Postfix 2.1	and later.

recipient_bcc_maps (default: empty)
       Optional	BCC (blind carbon-copy)	address	lookup tables, indexed by  re-
       cipient	address.  The BCC address (multiple results are	not supported)
       is added	when mail enters from outside of Postfix.

       This feature is available in Postfix 2.1	and later.

       The table search	order is as follows:

       o      Look up the "user+extension@domain.tld"  address	including  the
	      optional address extension.

       o      Look  up	the "user@domain.tld" address without the optional ad-
	      dress extension.

       o      Look up the "user+extension" address local part when the recipi-
	      ent domain equals	$myorigin, $mydestination, $inet_interfaces or
	      $proxy_interfaces.

       o      Look up the "user" address local part when the recipient	domain
	      equals $myorigin,	$mydestination,	$inet_interfaces or $proxy_in-
	      terfaces.

       o      Look up the "@domain.tld"	part.

       Specify the types and names of databases	to  use.   After  change,  run
       "postmap	/etc/postfix/recipient_bcc".

       Note:  if  mail	to  the	BCC address bounces it will be returned	to the
       sender.

       Note: automatic BCC recipients are produced  only  for  new  mail.   To
       avoid  mailer  loops,  automatic	BCC recipients are not generated after
       Postfix forwards	mail internally, or after Postfix generates  mail  it-
       self.

       Example:

       recipient_bcc_maps = hash:/etc/postfix/recipient_bcc

recipient_canonical_classes (default: envelope_recipient, header_recipient)
       What addresses are subject to recipient_canonical_maps address mapping.
       By default, recipient_canonical_maps address mapping is applied to  en-
       velope recipient	addresses, and to header recipient addresses.

       Specify one or more of: envelope_recipient, header_recipient

       This feature is available in Postfix 2.2	and later.

recipient_canonical_maps (default: empty)
       Optional	 address mapping lookup	tables for envelope and	header recipi-
       ent addresses.  The table format	and lookups are	documented in  canoni-
       cal(5).

       Note: $recipient_canonical_maps is processed before $canonical_maps.

       Example:

       recipient_canonical_maps	= hash:/etc/postfix/recipient_canonical

recipient_delimiter (default: empty)
       The  separator  between	user  names and	address	extensions (user+foo).
       See canonical(5), local(8), relocated(5)	and virtual(5) for the effects
       this has	on aliases, canonical, virtual,	relocated and on .forward file
       lookups.	 Basically, the	software tries user+foo	and  .forward+foo  be-
       fore trying user	and .forward.

       Example:

       recipient_delimiter = +

reject_code (default: 554)
       The  numerical  Postfix	SMTP  server  response code when a remote SMTP
       client request is rejected by the "reject" restriction.

       Do not change this unless you have  a  complete	understanding  of  RFC
       2821.

reject_tempfail_action (default: defer_if_permit)
       The  Postfix  SMTP server's action when a reject-type restriction fails
       due to a	temporary error	condition. Specify "defer" to defer the	remote
       SMTP client request immediately.	With the default "defer_if_permit" ac-
       tion, the Postfix SMTP server continues to look	for  opportunities  to
       reject  mail,  and defers the client request only if it would otherwise
       be accepted.

       For finer control, see:	unverified_recipient_tempfail_action,  unveri-
       fied_sender_tempfail_action,  unknown_address_tempfail_action,  and un-
       known_helo_hostname_tempfail_action.

       This feature is available in Postfix 2.6	and later.

relay_clientcerts (default: empty)
       List of tables with remote  SMTP	 client-certificate  fingerprints  for
       which  the  Postfix  SMTP  server  will	allow  access  with  the  per-
       mit_tls_clientcerts feature.  The fingerprint digest algorithm is  con-
       figurable via the smtpd_tls_fingerprint_digest parameter	(hard-coded as
       md5 prior to Postfix version 2.5).

       Postfix lookup tables are in the	form of	(key, value) pairs.  Since  we
       only  need  the	key, the value can be chosen freely, e.g.  the name of
       the  user  or   host:   D7:04:2F:A7:0B:8C:A5:21:FA:31:77:E1:41:8A:EE:80
       lutzpc.at.home

       Example:

       relay_clientcerts = hash:/etc/postfix/relay_clientcerts

       For  more fine-grained control, use check_ccert_access to select	an ap-
       propriate   access(5)   policy	for   each   client.	See   RESTRIC-
       TION_CLASS_README.

       This feature is available with Postfix version 2.2.

relay_destination_concurrency_limit   (default:	  $default_destination_concur-
       rency_limit)
       The maximal number of parallel deliveries to the	same  destination  via
       the  relay  message  delivery  transport. This limit is enforced	by the
       queue manager. The message delivery transport name is the  first	 field
       in the entry in the master.cf file.

       This feature is available in Postfix 2.0	and later.

relay_destination_recipient_limit    (default:	  $default_destination_recipi-
       ent_limit)
       The maximal number of recipients	per message for	the relay message  de-
       livery transport. This limit is enforced	by the queue manager. The mes-
       sage delivery transport name is the first field in  the	entry  in  the
       master.cf file.

       Setting	this  parameter	 to  a	value  of 1 changes the	meaning	of re-
       lay_destination_concurrency_limit from concurrency per domain into con-
       currency	per recipient.

       This feature is available in Postfix 2.0	and later.

relay_domains (default:	$mydestination)
       What  destination domains (and subdomains thereof) this system will re-
       lay mail	to. Subdomain  matching	 is  controlled	 with  the  parent_do-
       main_matches_subdomains	parameter. For details about how the relay_do-
       mains value is used, see	the description	of the permit_auth_destination
       and reject_unauth_destination SMTP recipient restrictions.

       Domains	that match $relay_domains are delivered	with the $relay_trans-
       port mail delivery transport. The SMTP server validates	recipient  ad-
       dresses with $relay_recipient_maps and rejects non-existent recipients.
       See also	the relay domains address class	 in  the  ADDRESS_CLASS_README
       file.

       Note: Postfix will not automatically forward mail for domains that list
       this  system  as	 their	primary	 or  backup  MX	 host.	See  the  per-
       mit_mx_backup restriction in the	postconf(5) manual page.

       Specify	a  list	 of  host  or  domain  names, "/file/name" patterns or
       "type:table" lookup tables,  separated  by  commas  and/or  whitespace.
       Continue	 long  lines  by  starting  the	 next  line with whitespace. A
       "/file/name" pattern is replaced	by its contents; a "type:table"	lookup
       table  is matched when a	(parent) domain	appears	as lookup key. Specify
       "!pattern" to exclude a domain from the list. The form "!/file/name" is
       supported only in Postfix version 2.4 and later.

relay_domains_reject_code (default: 554)
       The  numerical  Postfix SMTP server response code when a	client request
       is rejected by the reject_unauth_destination recipient restriction.

       Do not change this unless you have  a  complete	understanding  of  RFC
       2821.

relay_recipient_maps (default: empty)
       Optional	 lookup	 tables	 with  all valid addresses in the domains that
       match $relay_domains. Specify @domain as	a wild-card for	 domains  that
       have  no	valid recipient	list, and become a source of backscatter mail:
       Postfix accepts spam for	non-existent recipients	and then floods	 inno-
       cent  people  with undeliverable	mail.  Technically, tables listed with
       $relay_recipient_maps are used as lists:	Postfix	needs to know only  if
       a  lookup  string  is found or not, but it does not use the result from
       table lookup.

       If this parameter is non-empty, then the	Postfix	SMTP server  will  re-
       ject mail to unknown relay users. This feature is off by	default.

       See  also  the  relay domains address class in the ADDRESS_CLASS_README
       file.

       Example:

       relay_recipient_maps = hash:/etc/postfix/relay_recipients

       This feature is available in Postfix 2.0	and later.

relay_transport	(default: relay)
       The default mail	delivery transport and next-hop	destination for	remote
       delivery	 to domains listed with	$relay_domains.	In order of decreasing
       precedence, the nexthop destination  is	taken  from  $relay_transport,
       $sender_dependent_relayhost_maps, $relayhost, or	from the recipient do-
       main. This information can be overruled with the	transport(5) table.

       Specify a string	of the form transport:nexthop, where transport is  the
       name  of	 a mail	delivery transport defined in master.cf.  The :nexthop
       destination is optional;	its syntax is documented in the	manual page of
       the corresponding delivery agent.

       See  also  the  relay domains address class in the ADDRESS_CLASS_README
       file.

       This feature is available in Postfix 2.0	and later.

relayhost (default: empty)
       The next-hop destination	of non-local mail; overrides non-local domains
       in recipient addresses. This information	is overruled with relay_trans-
       port,	sender_dependent_default_transport_maps,    default_transport,
       sender_dependent_relayhost_maps and with	the transport(5) table.

       On  an intranet,	specify	the organizational domain name.	If your	inter-
       nal DNS uses no MX records, specify the name of	the  intranet  gateway
       host instead.

       In  the	case  of SMTP, specify a domain	name, hostname,	hostname:port,
       [hostname]:port,	[hostaddress] or [hostaddress]:port. The  form	[host-
       name] turns off MX lookups.

       If  you're  connected via UUCP, see the UUCP_README file	for useful in-
       formation.

       Examples:

       relayhost = $mydomain
       relayhost = [gateway.example.com]
       relayhost = uucphost
       relayhost = [an.ip.add.ress]

relocated_maps (default: empty)
       Optional	lookup tables with new contact information for	users  or  do-
       mains  that  no	longer	exist.	The table format and lookups are docu-
       mented in relocated(5).

       If you use this feature,	run "postmap /etc/postfix/relocated" to	 build
       the  necessary  DBM  or	DB file	after change, then "postfix reload" to
       make the	changes	visible.

       Examples:

       relocated_maps =	dbm:/etc/postfix/relocated
       relocated_maps =	hash:/etc/postfix/relocated

remote_header_rewrite_domain (default: empty)
       Don't rewrite message headers from remote clients at all	when this  pa-
       rameter	is  empty;  otherwise,	rewrite	message	headers	and append the
       specified domain	name to	incomplete  addresses.	 The  local_header_re-
       write_clients parameter controls	what clients Postfix considers local.

       Examples:

       The  safe  setting:  append  "domain.invalid"  to incomplete header ad-
       dresses from remote SMTP	clients, so that  those	 addresses  cannot  be
       confused	with local addresses.

	   remote_header_rewrite_domain	= domain.invalid

       The default, purist, setting: don't rewrite headers from	remote clients
       at all.

	   remote_header_rewrite_domain	=

require_home_directory (default: no)
       Require that a local(8) recipient's home	directory exists  before  mail
       delivery	 is  attempted.	 By  default this test is disabled.  It	can be
       useful for environments that import home	directories to the mail	server
       (IMPORTING HOME DIRECTORIES IS NOT RECOMMENDED).

reset_owner_alias (default: no)
       Reset  the local(8) delivery agent's idea of the	owner-alias attribute,
       when delivering mail to a child alias that does not have	its own	 owner
       alias.

       This  feature is	available in Postfix 2.8 and later. With older Postfix
       releases, the behavior is as if this parameter is set to	"yes".

       As documented in	aliases(5), when an alias name has a  companion	 alias
       named  owner-name,  delivery errors will	be reported to the owner alias
       instead of the sender. This configuration is  recommended  for  mailing
       lists.

       A less known property of	the owner alias	is that	it also	forces the lo-
       cal(8) delivery agent to	write local and	remote	addresses  from	 alias
       expansion to a new queue	file, instead of attempting to deliver mail to
       local addresses as soon as they come out	of alias expansion.

       Writing local addresses from alias expansion to a new queue file	allows
       for robust handling of temporary	delivery errors: errors	with one local
       member have no effect on	deliveries to other members of the  list.   On
       the other hand, delivery	to local addresses as soon as they come	out of
       alias expansion is fragile: a temporary error with  one	local  address
       from alias expansion will cause the entire alias	to be expanded repeat-
       edly until the error goes away, or until	the  message  expires  in  the
       queue.	In that	case, a	problem	with one list member results in	multi-
       ple message deliveries to other list members.

       The default behavior of Postfix 2.8 and later is	 to  keep  the	owner-
       alias  attribute	 of  the parent	alias, when delivering mail to a child
       alias that does not have	its own	owner  alias.  Then,  local  addresses
       from that child alias will be written to	a new queue file, and a	tempo-
       rary error with one local address will not  affect  delivery  to	 other
       mailing list members.

       Unfortunately,  older  Postfix releases reset the owner-alias attribute
       when delivering mail to a child alias that does not have	its own	 owner
       alias.	The local(8) delivery agent then attempts to deliver local ad-
       dresses as soon as they come out	of child alias expansion.  If delivery
       to  any address from child alias	expansion fails	with a temporary error
       condition, the entire mailing list may be expanded repeatedly until the
       mail expires in the queue, resulting in multiple	deliveries of the same
       message to mailing list members.

resolve_dequoted_address (default: yes)
       Resolve a recipient address safely instead of correctly,	by looking in-
       side quotes.

       By default, the Postfix address resolver	does not quote the address lo-
       calpart as per RFC 822, so that additional @ or % or !	operators  re-
       main  visible.  This behavior is	safe but it is also technically	incor-
       rect.

       If you specify "resolve_dequoted_address	= no", then  the  Postfix  re-
       solver  will  not know about additional @ etc. operators	in the address
       localpart. This opens opportunities for obscure mail relay attacks with
       user@domain@domain  addresses  when  Postfix provides backup MX service
       for Sendmail systems.

resolve_null_domain (default: no)
       Resolve an address that ends in the "@" null domain  as	if  the	 local
       hostname	were specified,	instead	of rejecting the address as invalid.

       This  feature  is available in Postfix 2.1 and later.  Earlier versions
       always resolve the null domain as the local hostname.

       The Postfix SMTP	server uses this feature to reject mail	from or	to ad-
       dresses	that  end  in the "@" null domain, and from addresses that re-
       write into a form that ends in the "@" null domain.

resolve_numeric_domain (default: no)
       Resolve "user@ipaddress"	as "user@[ipaddress]",	instead	 of  rejecting
       the address as invalid.

       This feature is available in Postfix 2.3	and later.

rewrite_service_name (default: rewrite)
       The  name  of  the address rewriting service. This service rewrites ad-
       dresses to standard form	and resolves them to a (delivery method, next-
       hop host, recipient) triple.

       This feature is available in Postfix 2.0	and later.

sample_directory (default: /etc/postfix)
       The  name  of  the  directory with example Postfix configuration	files.
       Starting	with Postfix 2.1, these	files  have  been  replaced  with  the
       postconf(5) manual page.

send_cyrus_sasl_authzid	(default: no)
       When  authenticating  to	 a remote SMTP or LMTP server with the default
       setting "no", send no SASL authoriZation	ID (authzid);  send  only  the
       SASL authentiCation ID (authcid)	plus the authcid's password.

       The  non-default	 setting  "yes"	 enables the behavior of older Postfix
       versions.  These	always send a SASL authzid that	is equal to  the  SASL
       authcid,	 but  this  causes  inter-operability  problems	with some SMTP
       servers.

       This feature is available in Postfix 2.4.4 and later.

sender_based_routing (default: no)
       This parameter should not be used. It  was  replaced  by	 sender_depen-
       dent_relayhost_maps in Postfix version 2.3.

sender_bcc_maps	(default: empty)
       Optional	 BCC  (blind  carbon-copy)  address  lookup tables, indexed by
       sender address.	The BCC	address	(multiple results are  not  supported)
       is added	when mail enters from outside of Postfix.

       This feature is available in Postfix 2.1	and later.

       The table search	order is as follows:

       o      Look  up	the  "user+extension@domain.tld" address including the
	      optional address extension.

       o      Look up the "user@domain.tld" address without the	 optional  ad-
	      dress extension.

       o      Look  up the "user+extension" address local part when the	sender
	      domain equals  $myorigin,	 $mydestination,  $inet_interfaces  or
	      $proxy_interfaces.

       o      Look  up	the  "user"  address local part	when the sender	domain
	      equals $myorigin,	$mydestination,	$inet_interfaces or $proxy_in-
	      terfaces.

       o      Look up the "@domain.tld"	part.

       Specify	the  types  and	 names of databases to use.  After change, run
       "postmap	/etc/postfix/sender_bcc".

       Note: if	mail to	the BCC	address	bounces	it will	 be  returned  to  the
       sender.

       Note:  automatic	 BCC  recipients  are  produced	only for new mail.  To
       avoid mailer loops, automatic BCC recipients are	 not  generated	 after
       Postfix	forwards  mail internally, or after Postfix generates mail it-
       self.

       Example:

       sender_bcc_maps = hash:/etc/postfix/sender_bcc

sender_canonical_classes (default: envelope_sender, header_sender)
       What addresses are subject to  sender_canonical_maps  address  mapping.
       By  default,  sender_canonical_maps address mapping is applied to enve-
       lope sender addresses, and to header sender addresses.

       Specify one or more of: envelope_sender,	header_sender

       This feature is available in Postfix 2.2	and later.

sender_canonical_maps (default:	empty)
       Optional	address	mapping	lookup tables for envelope and	header	sender
       addresses.   The	 table	format	and  lookups are documented in canoni-
       cal(5).

       Example:	you want to rewrite the	SENDER address	"user@ugly.domain"  to
       "user@pretty.domain", while still being able to send mail to the	RECIP-
       IENT address "user@ugly.domain".

       Note: $sender_canonical_maps is processed before	$canonical_maps.

       Example:

       sender_canonical_maps = hash:/etc/postfix/sender_canonical

sender_dependent_default_transport_maps	(default: empty)
       A sender-dependent override for the global default_transport  parameter
       setting.	 The  tables  are  searched by the envelope sender address and
       @domain.	A lookup result	of DUNNO terminates the	search	without	 over-
       riding  the  global default_transport parameter setting.	 This informa-
       tion is overruled with the transport(5) table.

       Note: this overrides default_transport, not transport_maps, and	there-
       fore  the  expected syntax is that of default_transport,	not the	syntax
       of transport_maps.  Specifically, this  does  not  support  the	trans-
       port_maps  syntax  for  null transport, null nexthop, or	null email ad-
       dresses.

       For safety reasons, this	feature	does not allow	$number	 substitutions
       in regular expression maps.

       This feature is available in Postfix 2.7	and later.

sender_dependent_relayhost_maps	(default: empty)
       A sender-dependent override for the global relayhost parameter setting.
       The tables are searched by the envelope sender address and  @domain.  A
       lookup  result  of  DUNNO  terminates the search	without	overriding the
       global relayhost	parameter setting (Postfix 2.6 and later). This	infor-
       mation	is   overruled	 with	relay_transport,  sender_dependent_de-
       fault_transport_maps, default_transport and with	the  transport(5)  ta-
       ble.

       For  safety  reasons, this feature does not allow $number substitutions
       in regular expression maps.

       This feature is available in Postfix 2.3	and later.

sendmail_path (default:	see postconf -d	output)
       A Sendmail compatibility	feature	that specifies	the  location  of  the
       Postfix	sendmail(1)  command.  This command can	be used	to submit mail
       into the	Postfix	queue.

service_throttle_time (default:	60s)
       How long	the Postfix master(8) waits before forking a server  that  ap-
       pears to	be malfunctioning.

       Time  units:  s (seconds), m (minutes), h (hours), d (days), w (weeks).
       The default time	unit is	s (seconds).

setgid_group (default: postdrop)
       The group ownership of set-gid Postfix commands and  of	group-writable
       Postfix	directories.  When this	parameter value	is changed you need to
       re-run "postfix set-permissions"	(with Postfix version 2.0 and earlier:
       "/etc/postfix/post-install set-permissions".

show_user_unknown_table_name (default: yes)
       Display	the  name  of  the  recipient  table in	the "User unknown" re-
       sponses.	 The extra detail makes	trouble	shooting easier	but  also  re-
       veals information that is nobody	elses business.

       This feature is available in Postfix 2.0	and later.

showq_service_name (default: showq)
       The name	of the showq(8)	service. This service produces mail queue sta-
       tus reports.

       This feature is available in Postfix 2.0	and later.

smtp_address_preference	(default: ipv6)
       The address type	("ipv6", "ipv4"	or "any") that the Postfix SMTP	client
       will  try  first,  when	a destination has IPv6 and IPv4	addresses with
       equal MX	preference. This feature has no	effect unless the  inet_proto-
       cols setting enables both IPv4 and IPv6.

       This feature is available in Postfix 2.8	and later.

smtp_always_send_ehlo (default:	yes)
       Always send EHLO	at the start of	an SMTP	session.

       With  "smtp_always_send_ehlo  =	no",  Postfix sends EHLO only when the
       word "ESMTP" appears  in	 the  server  greeting	banner	(example:  220
       spike.porcupine.org ESMTP Postfix).

smtp_bind_address (default: empty)
       An  optional  numerical	network	 address  that the Postfix SMTP	client
       should bind to when making an IPv4 connection.

       This can	be specified in	the main.cf file for all SMTP clients,	or  it
       can be specified	in the master.cf file for a specific client, for exam-
       ple:

	   /etc/postfix/master.cf:
	       smtp ...	smtp -o	smtp_bind_address=11.22.33.44

       Note 1: when inet_interfaces specifies no more than one	IPv4  address,
       and that	address	is a non-loopback address, it is automatically used as
       the smtp_bind_address.  This supports virtual IP	hosting, but can be  a
       problem on multi-homed firewalls. See the inet_interfaces documentation
       for more	detail.

       Note 2: address information may be enclosed inside [], but this form is
       not required here.

smtp_bind_address6 (default: empty)
       An  optional  numerical	network	 address  that the Postfix SMTP	client
       should bind to when making an IPv6 connection.

       This feature is available in Postfix 2.2	and later.

       This can	be specified in	the main.cf file for all SMTP clients,	or  it
       can be specified	in the master.cf file for a specific client, for exam-
       ple:

	   /etc/postfix/master.cf:
	       smtp ...	smtp -o	smtp_bind_address6=1:2:3:4:5:6:7:8

       Note 1: when inet_interfaces specifies no more than one	IPv6  address,
       and that	address	is a non-loopback address, it is automatically used as
       the smtp_bind_address6.	This supports virtual IP hosting, but can be a
       problem on multi-homed firewalls. See the inet_interfaces documentation
       for more	detail.

       Note 2: address information may be enclosed inside [], but this form is
       not recommended here.

smtp_body_checks (default: empty)
       Restricted  body_checks(5)  tables  for the Postfix SMTP	client.	 These
       tables are searched while mail is being delivered.  Actions that	change
       the delivery time or destination	are not	available.

       This feature is available in Postfix 2.5	and later.

smtp_cname_overrides_servername	(default: version dependent)
       Allow  DNS  CNAME  records  to override the servername that the Postfix
       SMTP client uses	for logging, SASL password lookup,  TLS	 policy	 deci-
       sions,  or TLS certificate verification.	The value "no" hardens Postfix
       smtp_tls_per_site hostname-based	policies against false hostname	infor-
       mation  in DNS CNAME records, and makes SASL password file lookups more
       predictable. This is the	default	setting	as of Postfix 2.3.

       This feature is available in Postfix 2.2.9 and later.

smtp_connect_timeout (default: 30s)
       The SMTP	client time limit for completing a  TCP	 connection,  or  zero
       (use the	operating system built-in time limit).

       When  no	 connection  can be made within	the deadline, the Postfix SMTP
       client tries the	next address on	the mail exchanger list. Specify 0  to
       disable the time	limit (i.e. use	whatever timeout is implemented	by the
       operating system).

       Time units: s (seconds),	m (minutes), h (hours),	d (days),  w  (weeks).
       The default time	unit is	s (seconds).

smtp_connection_cache_destinations (default: empty)
       Permanently  enable  SMTP connection caching for	the specified destina-
       tions.  With SMTP connection caching, a connection is not closed	 imme-
       diately	after  completion of a mail transaction.  Instead, the connec-
       tion is kept open for up	to $smtp_connection_cache_time_limit  seconds.
       This  allows connections	to be reused for other deliveries, and can im-
       prove mail delivery performance.

       Specify a comma or  white  space	 separated  list  of  destinations  or
       pseudo-destinations:

       o      if  mail is sent without a relay host: a domain name (the	right-
	      hand side	of an email address, without the [] around  a  numeric
	      IP address),

       o      if  mail is sent via a relay host: a relay host name (without []
	      or non-default TCP port),	as specified  in  main.cf  or  in  the
	      transport	map,

       o      if  mail	is  sent via a UNIX-domain socket: a pathname (without
	      the unix:	prefix),

       o      a	/file/name with	domain names and/or relay host	names  as  de-
	      fined above,

       o      a	 "type:table" with domain names	and/or relay host names	on the
	      left-hand	side.  The right-hand side  result  from  "type:table"
	      lookups is ignored.

       This feature is available in Postfix 2.2	and later.

smtp_connection_cache_on_demand	(default: yes)
       Temporarily  enable  SMTP  connection caching while a destination has a
       high volume of mail in the active queue.	 With SMTP connection caching,
       a  connection  is  not  closed  immediately  after completion of	a mail
       transaction.  Instead, the connection is	kept open for up to $smtp_con-
       nection_cache_time_limit	seconds.  This allows connections to be	reused
       for other deliveries, and can improve mail delivery performance.

       This feature is available in Postfix 2.2	and later.

smtp_connection_cache_reuse_limit (default: 10)
       When SMTP connection caching is enabled,	the number of  times  that  an
       SMTP session may	be reused before it is closed.

       This feature is available in Postfix 2.2. In Postfix 2.3	it is replaced
       by $smtp_connection_reuse_time_limit.

smtp_connection_cache_time_limit (default: 2s)
       When SMTP connection caching is enabled,	the amount of time that	an un-
       used SMTP client	socket is kept open before it is closed.  Do not spec-
       ify larger values without permission from the remote sites.

       This feature is available in Postfix 2.2	and later.

smtp_connection_reuse_time_limit (default: 300s)
       The amount of time during which Postfix will use	an SMTP	connection re-
       peatedly.   The	timer starts when the connection is initiated (i.e. it
       includes	the connect, greeting and helo latency,	in addition to the la-
       tencies of subsequent mail delivery transactions).

       This feature addresses a	performance stability problem with remote SMTP
       servers.	This problem is	not specific to	Postfix: it  can  happen  when
       any  MTA	 sends large amounts of	SMTP email to a	site that has multiple
       MX hosts.

       The problem starts when one of a	set of MX hosts	 becomes  slower  than
       the  rest.   Even though	SMTP clients connect to	fast and slow MX hosts
       with equal probability, the slow	MX host	ends up	with more simultaneous
       inbound	connections than the faster MX hosts, because the slow MX host
       needs more time to serve	each client request.

       The slow	MX host	becomes	a connection attractor.	 If one	 MX  host  be-
       comes  N	times slower than the rest, it dominates mail delivery latency
       unless there are	more than N fast MX hosts to counter the  effect.  And
       if  the number of MX hosts is smaller than N, the mail delivery latency
       becomes effectively that	of the slowest MX host divided	by  the	 total
       number of MX hosts.

       The solution uses connection caching in a way that differs from Postfix
       version 2.2.  By	limiting the amount of time during which a  connection
       can  be	used  repeatedly (instead of limiting the number of deliveries
       over that connection), Postfix not only restores	fairness in  the  dis-
       tribution of simultaneous connections across a set of MX	hosts, it also
       favors deliveries over connections that perform well, which is  exactly
       what we want.

       The  default  reuse time	limit, 300s, is	comparable to the various smtp
       transaction timeouts which are fair estimates of	maximum	excess latency
       for  a slow delivery.  Note that	hosts may accept thousands of messages
       over a single connection	 within	 the  default  connection  reuse  time
       limit.  This number is much larger than the default Postfix version 2.2
       limit of	10 messages per	cached connection. It may prove	 necessary  to
       lower the limit to avoid	interoperability issues	with MTAs that exhibit
       bugs when many messages are delivered via a single connection.  A lower
       reuse  time limit risks losing the benefit of connection	reuse when the
       average connection and mail delivery latency  exceeds  the  reuse  time
       limit.

       This feature is available in Postfix 2.3	and later.

smtp_data_done_timeout (default: 600s)
       The  SMTP client	time limit for sending the SMTP	".", and for receiving
       the server response.

       When no response	is received within the deadline, a warning  is	logged
       that the	mail may be delivered multiple times.

       Time  units:  s (seconds), m (minutes), h (hours), d (days), w (weeks).
       The default time	unit is	s (seconds).

smtp_data_init_timeout (default: 120s)
       The SMTP	client time limit for sending the SMTP DATA command,  and  for
       receiving the server response.

       Time  units:  s (seconds), m (minutes), h (hours), d (days), w (weeks).
       The default time	unit is	s (seconds).

smtp_data_xfer_timeout (default: 180s)
       The SMTP	client time limit for sending the SMTP message content.	  When
       the  connection makes no	progress for more than $smtp_data_xfer_timeout
       seconds the Postfix SMTP	client terminates the transfer.

       Time units: s (seconds),	m (minutes), h (hours),	d (days),  w  (weeks).
       The default time	unit is	s (seconds).

smtp_defer_if_no_mx_address_found (default: no)
       Defer mail delivery when	no MX record resolves to an IP address.

       The  default  (no)  is  to return the mail as undeliverable. With older
       Postfix versions	the default was	to keep	trying to deliver the mail un-
       til someone fixed the MX	record or until	the mail was too old.

       Note:  Postfix always ignores MX	records	with equal or worse preference
       than the	local MTA itself.

       This feature is available in Postfix 2.1	and later.

smtp_destination_concurrency_limit   (default:	  $default_destination_concur-
       rency_limit)
       The  maximal  number of parallel	deliveries to the same destination via
       the smtp	message	delivery transport. This  limit	 is  enforced  by  the
       queue  manager.	The message delivery transport name is the first field
       in the entry in the master.cf file.

smtp_destination_recipient_limit    (default:	  $default_destination_recipi-
       ent_limit)
       The  maximal  number of recipients per message for the smtp message de-
       livery transport. This limit is enforced	by the queue manager. The mes-
       sage  delivery  transport  name	is the first field in the entry	in the
       master.cf file.

       Setting this parameter to a value of 1 changes the meaning of smtp_des-
       tination_concurrency_limit from concurrency per domain into concurrency
       per recipient.

smtp_discard_ehlo_keyword_address_maps (default: empty)
       Lookup tables, indexed by the remote SMTP server	address, with case in-
       sensitive  lists	 of  EHLO  keywords (pipelining, starttls, auth, etc.)
       that the	Postfix	SMTP client will ignore	in the EHLO  response  from  a
       remote SMTP server. See smtp_discard_ehlo_keywords for details. The ta-
       ble  is	not  indexed  by  hostname  for	 consistency  with  smtpd_dis-
       card_ehlo_keyword_address_maps.

       This feature is available in Postfix 2.2	and later.

smtp_discard_ehlo_keywords (default: empty)
       A  case	insensitive list of EHLO keywords (pipelining, starttls, auth,
       etc.) that the Postfix SMTP client will ignore  in  the	EHLO  response
       from a remote SMTP server.

       This feature is available in Postfix 2.2	and later.

       Notes:

       o      Specify the silent-discard pseudo	keyword	to prevent this	action
	      from being logged.

       o      Use the smtp_discard_ehlo_keyword_address_maps feature  to  dis-
	      card EHLO	keywords selectively.

smtp_dns_resolver_options (default: empty)
       DNS Resolver options for	the Postfix SMTP client.  Specify zero or more
       of the following	options, separated by  comma  or  whitespace.	Option
       names  are  case-sensitive. Some	options	refer to domain	names that are
       specified in the	file /etc/resolv.conf or equivalent.

       res_defnames
	      Append the current domain	name to	single-component names	(those
	      that do not contain a "."	character). This can produce incorrect
	      results, and is the hard-coded behavior prior to Postfix 2.8.

       res_dnsrch
	      Search for host names in the current domain and  in  parent  do-
	      mains.  This  can	produce	incorrect results and is therefore not
	      recommended.

       This feature is available in Postfix 2.8	and later.

smtp_enforce_tls (default: no)
       Enforcement mode: require that remote SMTP servers use TLS  encryption,
       and  never  send	mail in	the clear.  This also requires that the	remote
       SMTP server hostname matches the	information in the remote server  cer-
       tificate,  and  that the	remote SMTP server certificate was issued by a
       CA that is trusted by the  Postfix  SMTP	 client.  If  the  certificate
       doesn't	verify or the hostname doesn't match, delivery is deferred and
       mail stays in the queue.

       The server hostname is matched against all names	provided  as  dNSNames
       in  the SubjectAlternativeName.	If no dNSNames are specified, the Com-
       monName is checked.  The	behavior may be	changed	with the  smtp_tls_en-
       force_peername option.

       This  option  is	 useful	 only if you are definitely sure that you will
       only connect to servers that support RFC	2487 _and_ that	provide	 valid
       server  certificates.   Typical	use is for clients that	send all their
       email to	a dedicated mailhub.

       This feature is available in Postfix 2.2	and later.  With  Postfix  2.3
       and later use smtp_tls_security_level instead.

smtp_fallback_relay (default: $fallback_relay)
       Optional	 list of relay hosts for SMTP destinations that	can't be found
       or that are unreachable.	With Postfix 2.2 and earlier this parameter is
       called fallback_relay.

       By  default,  mail  is returned to the sender when a destination	is not
       found, and delivery is deferred when a destination is unreachable.

       The fallback relays must	be SMTP	destinations. Specify a	domain,	 host,
       host:port,  [host]:port,	 [address]  or [address]:port; the form	[host]
       turns off MX lookups.  If you specify multiple SMTP destinations, Post-
       fix will	try them in the	specified order.

       To  prevent  mailer loops between MX hosts and fall-back	hosts, Postfix
       version 2.2 and later will not use the fallback relays for destinations
       that it is MX host for (assuming	DNS lookup is turned on).

smtp_generic_maps (default: empty)
       Optional	 lookup	 tables	 that  perform	address	 rewriting in the SMTP
       client, typically to transform a	locally	valid address into a  globally
       valid  address  when  sending mail across the Internet.	This is	needed
       when the	local machine does not have its	own Internet domain name,  but
       uses something like localdomain.local instead.

       The table format	and lookups are	documented in generic(5); examples are
       shown in	the ADDRESS_REWRITING_README and STANDARD_CONFIGURATION_README
       documents.

       This feature is available in Postfix 2.2	and later.

smtp_header_checks (default: empty)
       Restricted  header_checks(5) tables for the Postfix SMTP	client.	 These
       tables are searched while mail is being delivered.  Actions that	change
       the delivery time or destination	are not	available.

       This feature is available in Postfix 2.5	and later.

smtp_helo_name (default: $myhostname)
       The hostname to send in the SMTP	EHLO or	HELO command.

       The  default  value  is	the  machine  hostname.	 Specify a hostname or
       [ip.add.re.ss].

       This information	can be specified in the	 main.cf  file	for  all  SMTP
       clients,	 or  it	 can be	specified in the master.cf file	for a specific
       client, for example:

	   /etc/postfix/master.cf:
	       mysmtp ... smtp -o smtp_helo_name=foo.bar.com

       This feature is available in Postfix 2.0	and later.

smtp_helo_timeout (default: 300s)
       The SMTP	client time limit for sending the HELO or  EHLO	 command,  and
       for receiving the initial server	response.

       Time  units:  s (seconds), m (minutes), h (hours), d (days), w (weeks).
       The default time	unit is	s (seconds).

smtp_host_lookup (default: dns)
       What mechanisms the Postfix SMTP	client uses to look up a host's	IP ad-
       dress.	This  parameter	is ignored when	DNS lookups are	disabled (see:
       disable_dns_lookups).

       Specify one of the following:

       dns    Hosts can	be found in the	DNS (preferred).

       native Use the native naming service only (nsswitch.conf, or equivalent
	      mechanism).

       dns, native
	      Use the native service for hosts not found in the	DNS.

       This feature is available in Postfix 2.1	and later.

smtp_line_length_limit (default: 990)
       The  maximal  length of message header and body lines that Postfix will
       send via	SMTP.  Longer lines are	broken by inserting "<CR><LF><SPACE>".
       This minimizes the damage to MIME formatted mail.

       By  default, the	line length is limited to 990 characters, because some
       server implementations cannot receive mail with long lines.

smtp_mail_timeout (default: 300s)
       The SMTP	client time limit for sending the MAIL FROM command,  and  for
       receiving the server response.

       Time  units:  s (seconds), m (minutes), h (hours), d (days), w (weeks).
       The default time	unit is	s (seconds).

smtp_mime_header_checks	(default: empty)
       Restricted mime_header_checks(5)	tables for the	Postfix	 SMTP  client.
       These  tables are searched while	mail is	being delivered.  Actions that
       change the delivery time	or destination are not available.

       This feature is available in Postfix 2.5	and later.

smtp_mx_address_limit (default:	5)
       The maximal number of MX	(mail exchanger) IP addresses that can	result
       from  mail exchanger lookups, or	zero (no limit). Prior to Postfix ver-
       sion 2.3, this limit was	disabled by default.

       This feature is available in Postfix 2.1	and later.

smtp_mx_session_limit (default:	2)
       The maximal number of SMTP sessions per delivery	request	before	giving
       up  or  delivering  to a	fall-back relay	host, or zero (no limit). This
       restriction ignores sessions that fail to  complete  the	 SMTP  initial
       handshake  (Postfix  version  2.2 and earlier) or that fail to complete
       the EHLO	and TLS	handshake (Postfix version 2.3 and later).

       This feature is available in Postfix 2.1	and later.

smtp_nested_header_checks (default: empty)
       Restricted nested_header_checks(5) tables for the Postfix SMTP  client.
       These  tables are searched while	mail is	being delivered.  Actions that
       change the delivery time	or destination are not available.

       This feature is available in Postfix 2.5	and later.

smtp_never_send_ehlo (default: no)
       Never send EHLO at the start of an SMTP session.	See also the  smtp_al-
       ways_send_ehlo parameter.

smtp_pix_workaround_delay_time (default: 10s)
       How  long  the Postfix SMTP client pauses before	sending	".<CR><LF>" in
       order to	work around the	PIX firewall "<CR><LF>.<CR><LF>" bug.

       Choosing	a too short time makes this workaround ineffective when	 send-
       ing large messages over slow network connections.

smtp_pix_workaround_maps (default: empty)
       Lookup tables, indexed by the remote SMTP server	address, with per-des-
       tination	workarounds for	CISCO PIX firewall bugs.  The table is not in-
       dexed  by  hostname  for	consistency with smtp_discard_ehlo_keyword_ad-
       dress_maps.

       This feature is available in Postfix 2.4	and later.

smtp_pix_workaround_threshold_time (default: 500s)
       How long	a message must be queued before	the Postfix SMTP client	 turns
       on  the	PIX  firewall  "<CR><LF>.<CR><LF>" bug workaround for delivery
       through firewalls with "smtp fixup" mode	turned on.

       By default, the workaround is turned off	for mail that  is  queued  for
       less  than  500	seconds.  In  other  words, the	workaround is normally
       turned off for the first	delivery attempt.

       Specify 0 to enable the PIX firewall "<CR><LF>.<CR><LF>"	bug workaround
       upon the	first delivery attempt.

smtp_pix_workarounds (default: disable_esmtp, delay_dotcrlf)
       A  list	that specifies zero or more workarounds	for CISCO PIX firewall
       bugs. These workarounds are implemented by  the	Postfix	 SMTP  client.
       Workaround names	are separated by comma or space, and are case insensi-
       tive.  This parameter setting can  be  overruled	 with  per-destination
       smtp_pix_workaround_maps	settings.

       delay_dotcrlf
	      Insert  a	 delay before sending ".<CR><LF>" after	the end	of the
	      message content.	The delay is  subject  to  the	smtp_pix_work-
	      around_delay_time	and smtp_pix_workaround_threshold_time parame-
	      ter settings.

       disable_esmtp
	      Disable all extended SMTP	commands: send HELO instead of EHLO.

       This feature is available in Postfix 2.4	and later.  The	 default  set-
       tings are backwards compatible with earlier Postfix versions.

smtp_quit_timeout (default: 300s)
       The  SMTP  client  time limit for sending the QUIT command, and for re-
       ceiving the server response.

       Time units: s (seconds),	m (minutes), h (hours),	d (days),  w  (weeks).
       The default time	unit is	s (seconds).

smtp_quote_rfc821_envelope (default: yes)
       Quote  addresses	 in SMTP MAIL FROM and RCPT TO commands	as required by
       RFC 2821. This includes putting quotes around an	address	localpart that
       ends in ".".

       The  default  is	to comply with RFC 2821. If you	have to	send mail to a
       broken SMTP server, configure a special SMTP client in master.cf:

	   /etc/postfix/master.cf:
	       broken-smtp . . . smtp -o smtp_quote_rfc821_envelope=no

       and route mail for the destination in  question	to  the	 "broken-smtp"
       message delivery	with a transport(5) table.

       This feature is available in Postfix 2.1	and later.

smtp_randomize_addresses (default: yes)
       Randomize  the  order of	equal-preference MX host addresses.  This is a
       performance feature of the Postfix SMTP client.

smtp_rcpt_timeout (default: 300s)
       The SMTP	client time limit for sending the SMTP RCPT  TO	 command,  and
       for receiving the server	response.

       Time  units:  s (seconds), m (minutes), h (hours), d (days), w (weeks).
       The default time	unit is	s (seconds).

smtp_reply_filter (default: empty)
       A mechanism to transform	replies	from remote SMTP servers one line at a
       time.   This  is	 a last-resort tool to work around server replies that
       break inter-operability with the	Postfix	SMTP client.  Other  uses  in-
       volve fault injection to	test Postfix's handling	of invalid responses.

       Notes:

       o      In  the case of a	multi-line reply, the Postfix SMTP client uses
	      the final	reply line's numerical SMTP reply  code	 and  enhanced
	      status code.

       o      The  numerical  SMTP  reply code (XYZ) takes precedence over the
	      enhanced status code (X.Y.Z).  When  the	enhanced  status  code
	      initial digit differs from the SMTP reply	code initial digit, or
	      when no enhanced status code is present, the Postfix SMTP	client
	      uses a generic enhanced status code (X.0.0) instead.

       Specify the name	of a "type:table" lookup table.	The search string is a
       single SMTP reply line as received from the remote SMTP server,	except
       that the	trailing <CR><LF> are removed.

       Examples:

       /etc/postfix/main.cf:
	   smtp_reply_filter = pcre:/etc/postfix/reply_filter

       /etc/postfix/reply_filter:
	   # Transform garbage into "250-filler..." so that it looks like
	   # one line from a multi-line	reply. It does not matter what we
	   # substitute	here as	long it	has the	right syntax.  The Postfix
	   # SMTP client will use the final line's numerical SMTP reply
	   # code and enhanced status code.
	   !/^([2-5][0-9][0-9]($|[- ]))/ 250-filler for	garbage

       This feature is available in Postfix 2.7.

smtp_rset_timeout (default: 20s)
       The  SMTP  client  time limit for sending the RSET command, and for re-
       ceiving the server response. The	SMTP client sends  RSET	 in  order  to
       finish a	recipient address probe, or to verify that a cached session is
       still usable.

       This feature is available in Postfix 2.1	and later.

smtp_sasl_auth_cache_name (default: empty)
       An optional table to prevent repeated SASL authentication failures with
       the same	remote SMTP server hostname, username and password. Each table
       (key, value) pair contains a server name, a username and	password,  and
       the full	server response. This information is stored when a remote SMTP
       server rejects an authentication	attempt	with a	535  reply  code.   As
       long  as	the smtp_sasl_password_maps information	does no	change,	and as
       long as the smtp_sasl_auth_cache_name information does not expire  (see
       smtp_sasl_auth_cache_time)  the Postfix SMTP client avoids SASL authen-
       tication	attempts with the same server, username	and password, and  in-
       stead	bounces	   or	 defers	   mail	  as   controlled   with   the
       smtp_sasl_auth_soft_bounce configuration	parameter.

       Use  a  per-destination	delivery  concurrency  of  1   (for   example,
       "smtp_destination_concurrency_limit  =  1",  "relay_destination_concur-
       rency_limit = 1", etc.),	otherwise multiple delivery agents may experi-
       ence a login failure at the same	time.

       The  table  must	 be  accessed via the proxywrite service, i.e. the map
       name must start with "proxy:". The table	should be stored under the di-
       rectory specified with the data_directory parameter.

       This  feature  uses  cryptographic  hashing to protect plain-text pass-
       words, and requires that	Postfix	is compiled with TLS support.

       Example:

       smtp_sasl_auth_cache_name = proxy:btree:/var/db/postfix/sasl_auth_cache

       This feature is available in Postfix 2.5	and later.

smtp_sasl_auth_cache_time (default: 90d)
       The maximal age of an smtp_sasl_auth_cache_name entry before it is  re-
       moved.

       This feature is available in Postfix 2.5	and later.

smtp_sasl_auth_enable (default:	no)
       Enable SASL authentication in the Postfix SMTP client.  By default, the
       Postfix SMTP client uses	no authentication.

       Example:

       smtp_sasl_auth_enable = yes

smtp_sasl_auth_soft_bounce (default: yes)
       When a remote SMTP server rejects a SASL	authentication request with  a
       535  reply code,	defer mail delivery instead of returning mail as unde-
       liverable. The latter behavior was hard-coded prior to Postfix  version
       2.5.

       Note: the setting "yes" overrides the global soft_bounce	parameter, but
       the setting "no"	does not.

       Example:

       # Default as of Postfix 2.5
       smtp_sasl_auth_soft_bounce = yes
       # The old hard-coded default
       smtp_sasl_auth_soft_bounce = no

       This feature is available in Postfix 2.5	and later.

smtp_sasl_mechanism_filter (default: empty)
       If non-empty, a Postfix SMTP client filter for the remote SMTP server's
       list of offered SASL mechanisms.	 Different client and server implemen-
       tations may support different mechanism lists. By default, the  Postfix
       SMTP  client  will  use	the  intersection of the two. smtp_sasl_mecha-
       nism_filter further restricts what server mechanisms  the  client  will
       take into consideration.

       Specify	mechanism  names, "/file/name" patterns	or "type:table"	lookup
       tables. The right-hand side result from	"type:table"  lookups  is  ig-
       nored.  Specify	"!pattern"  to exclude a mechanism name	from the list.
       The form	"!/file/name" is supported only	in  Postfix  version  2.4  and
       later.

       This feature is available in Postfix 2.2	and later.

       Examples:

       smtp_sasl_mechanism_filter = plain, login
       smtp_sasl_mechanism_filter = /etc/postfix/smtp_mechs
       smtp_sasl_mechanism_filter = !gssapi, !login, static:rest

smtp_sasl_password_maps	(default: empty)
       Optional	SMTP client lookup tables with one username:password entry per
       remote hostname or domain, or sender address when sender-dependent  au-
       thentication  is	enabled.  If no	username:password entry	is found, then
       the Postfix SMTP	client will not	attempt	to authenticate	to the	remote
       host.

       The  Postfix  SMTP client opens the lookup table	before going to	chroot
       jail, so	you can	leave the password file	in /etc/postfix.

smtp_sasl_path (default: empty)
       Implementation-specific information that	the Postfix SMTP client	passes
       through	to  the	 SASL  plug-in	implementation	that  is selected with
       smtp_sasl_type.	Typically this specifies the name of  a	 configuration
       file or rendezvous point.

       This feature is available in Postfix 2.3	and later.

smtp_sasl_security_options (default: noplaintext, noanonymous)
       Postfix	SMTP  client SASL security options; as of Postfix 2.3 the list
       of available features depends on	the SASL client	implementation that is
       selected	with smtp_sasl_type.

       The  following  security	features are defined for the cyrus client SASL
       implementation:

       Specify zero or more of the following:

       noplaintext
	      Disallow methods that use	plaintext passwords.

       noactive
	      Disallow methods subject to active (non-dictionary) attack.

       nodictionary
	      Disallow methods subject to passive (dictionary) attack.

       noanonymous
	      Disallow methods that allow anonymous authentication.

       mutual_auth
	      Only allow  methods  that	 provide  mutual  authentication  (not
	      available	with SASL version 1).

       Example:

       smtp_sasl_security_options = noplaintext

smtp_sasl_tls_security_options (default: $smtp_sasl_security_options)
       The  SASL  authentication security options that the Postfix SMTP	client
       uses for	TLS encrypted SMTP sessions.

       This feature is available in Postfix 2.2	and later.

smtp_sasl_tls_verified_security_options	(default:  $smtp_sasl_tls_security_op-
       tions)
       The  SASL  authentication security options that the Postfix SMTP	client
       uses for	TLS encrypted SMTP sessions with a  verified  server  certifi-
       cate.

       When  mail  is  sent  to	the public MX host for the recipient's domain,
       server certificates are by default optional, and	delivery proceeds even
       if  certificate	verification fails. For	delivery via a submission ser-
       vice that requires SASL authentication, it may be appropriate  to  send
       plaintext  passwords only when the connection to	the server is strongly
       encrypted and the server	identity is verified.

       The smtp_sasl_tls_verified_security_options parameter makes it possible
       to  only	 enable	 plaintext  mechanisms when a secure connection	to the
       server is available. Submission servers subject to this policy must ei-
       ther  have verifiable certificates or offer suitable non-plaintext SASL
       mechanisms.

       This feature is available in Postfix 2.6	and later.

smtp_sasl_type (default: cyrus)
       The SASL	plug-in	type that the Postfix SMTP client should use  for  au-
       thentication.   The  available  types are listed	with the "postconf -A"
       command.

       This feature is available in Postfix 2.3	and later.

smtp_send_xforward_command (default: no)
       Send the	non-standard XFORWARD command when  the	 Postfix  SMTP	server
       EHLO response announces XFORWARD	support.

       This  allows  an	 "smtp"	delivery agent,	used for injecting mail	into a
       content filter, to forward the name, address, protocol and HELO name of
       the  original  client to	the content filter and downstream queuing SMTP
       server. This can	produce	more useful logging than  localhost[127.0.0.1]
       etc.

       This feature is available in Postfix 2.1	and later.

smtp_sender_dependent_authentication (default: no)
       Enable sender-dependent authentication in the Postfix SMTP client; this
       is available only with SASL authentication, and disables	 SMTP  connec-
       tion  caching  to  ensure that mail from	different senders will use the
       appropriate credentials.

       This feature is available in Postfix 2.3	and later.

smtp_skip_4xx_greeting (default: yes)
       Skip SMTP servers that greet with a 4XX status code (go away, try again
       later).

       By   default,  Postfix  moves  on  the  next  mail  exchanger.  Specify
       "smtp_skip_4xx_greeting = no" if	Postfix	should defer delivery  immedi-
       ately.

       This  feature  is  available in Postfix 2.0 and earlier.	 Later Postfix
       versions	always skip SMTP servers that greet with a 4XX status code.

smtp_skip_5xx_greeting (default: yes)
       Skip SMTP servers that greet with a 5XX status code (go	away,  do  not
       try again later).

       By  default,  the Postfix SMTP client moves on the next mail exchanger.
       Specify "smtp_skip_5xx_greeting = no" if	Postfix	should bounce the mail
       immediately.  The default setting is incorrect, but it is what a	lot of
       people expect to	happen.

smtp_skip_quit_response	(default: yes)
       Do not wait for the response to the SMTP	QUIT command.

smtp_starttls_timeout (default:	300s)
       Time limit for Postfix SMTP client write	and read operations during TLS
       startup and shutdown handshake procedures.

       This feature is available in Postfix 2.2	and later.

smtp_tls_CAfile	(default: empty)
       A  file	containing  CA certificates of root CAs	trusted	to sign	either
       remote SMTP server certificates or intermediate CA certificates.	 These
       are  loaded  into  memory  before  the smtp(8) client enters the	chroot
       jail.  If  the  number  of  trusted  roots  is  large,  consider	 using
       smtp_tls_CApath	instead,  but  note  that the latter directory must be
       present in the chroot jail if the smtp(8) client	is chrooted. This file
       may  also be used to augment the	client certificate trust chain,	but it
       is  best	 to  include  all  the	required  certificates	 directly   in
       $smtp_tls_cert_file.

       Specify	"tls_append_default_CA = no" to	prevent	Postfix	from appending
       the system-supplied default CAs and trusting third-party	certificates.

       Example:

       smtp_tls_CAfile = /etc/postfix/CAcert.pem

       This feature is available in Postfix 2.2	and later.

smtp_tls_CApath	(default: empty)
       Directory with PEM format certificate authority certificates  that  the
       Postfix	SMTP  client  uses to verify a remote SMTP server certificate.
       Don't forget to create the necessary "hash" links  with,	 for  example,
       "$OPENSSL_HOME/bin/c_rehash /etc/postfix/certs".

       To  use	this option in chroot mode, this directory (or a copy) must be
       inside the chroot jail.

       Specify "tls_append_default_CA =	no" to prevent Postfix from  appending
       the system-supplied default CAs and trusting third-party	certificates.

       Example:

       smtp_tls_CApath = /etc/postfix/certs

       This feature is available in Postfix 2.2	and later.

smtp_tls_block_early_mail_reply	(default: no)
       Try  to detect a	mail hijacking attack based on a TLS protocol vulnera-
       bility (CVE-2009-3555), where  an  attacker  prepends  malicious	 HELO,
       MAIL,  RCPT,  DATA  commands to a Postfix SMTP client TLS session.  The
       attack would succeed with non-Postfix SMTP servers that	reply  to  the
       malicious HELO, MAIL, RCPT, DATA	commands after negotiating the Postfix
       SMTP client TLS session.

       This feature is available in Postfix 2.7.

smtp_tls_cert_file (default: empty)
       File with the Postfix SMTP client RSA certificate in PEM	format.	  This
       file  may  also	contain	 the  Postfix SMTP client private RSA key, and
       these may be the	same as	the Postfix SMTP server	 RSA  certificate  and
       key file.

       Do not configure	client certificates unless you must present client TLS
       certificates to one or more servers. Client certificates	are  not  usu-
       ally  needed,  and  can cause problems in configurations	that work well
       without them. The recommended setting is	to let the defaults stand:

	   smtp_tls_cert_file =
	   smtp_tls_key_file =
	   smtp_tls_dcert_file =
	   smtp_tls_dkey_file =
	   smtp_tls_eccert_file	=
	   smtp_tls_eckey_file =

       The best	way to use the default settings	is to comment  out  the	 above
       parameters in main.cf if	present.

       To  enable  remote  SMTP	servers	to verify the Postfix SMTP client cer-
       tificate, the issuing CA	certificates must be  made  available  to  the
       server. You should include the required certificates in the client cer-
       tificate	file, the client certificate first,  then  the	issuing	 CA(s)
       (bottom-up order).

       Example:	the certificate	for "client.example.com" was issued by "inter-
       mediate CA" which itself	has a certificate issued by "root CA".	Create
       the  client.pem	file  with  "cat  client_cert.pem  intermediate_CA.pem
       root_CA.pem > client.pem".

       If you also want	to verify remote SMTP server  certificates  issued  by
       these  CAs,  you	can add	the CA certificates to the smtp_tls_CAfile, in
       which case it is	not necessary to have them in the  smtp_tls_cert_file,
       smtp_tls_dcert_file or smtp_tls_eccert_file.

       A certificate supplied here must	be usable as an	SSL client certificate
       and hence pass the "openssl verify -purpose sslclient ..." test.

       Example:

       smtp_tls_cert_file = /etc/postfix/client.pem

       This feature is available in Postfix 2.2	and later.

smtp_tls_cipherlist (default: empty)
       Obsolete	Postfix	< 2.3 control for the Postfix SMTP client  TLS	cipher
       list. As	this feature applies to	all TLS	security levels, it is easy to
       create inter-operability	problems  by  choosing	a  non-default	cipher
       list.  Do  not  use a non-default TLS cipher list on hosts that deliver
       email to	the public Internet: you will  be  unable  to  send  email  to
       servers	that  only support the ciphers you exclude. Using a restricted
       cipher list may be more appropriate for an internal MTA,	where one  can
       exert  some  control  over  the	TLS  software and settings of the peer
       servers.

       Note: do	not use	"" quotes around the parameter value.

       This feature is available in Postfix version 2.2. It is not  used  with
       Postfix 2.3 and later; use smtp_tls_mandatory_ciphers instead.

smtp_tls_ciphers (default: export)
       The minimum TLS cipher grade that the Postfix SMTP client will use with
       opportunistic TLS  encryption.  Cipher  types  listed  in  smtp_tls_ex-
       clude_ciphers are excluded from the base	definition of the selected ci-
       pher grade. The default value "export" ensures maximum  inter-operabil-
       ity.  Because  encryption is optional, stronger controls	are not	appro-
       priate, and this	setting	SHOULD NOT be changed unless the change	is es-
       sential.

       When   TLS   is	 mandatory   the   cipher  grade  is  chosen  via  the
       smtp_tls_mandatory_ciphers configuration	parameter, see there for  syn-
       tax details. See	smtp_tls_policy_maps for information on	how to config-
       ure ciphers on a	per-destination	basis.

       Example:
       smtp_tls_ciphers	= export

       This feature is available in Postfix 2.6	and later. With	earlier	 Post-
       fix  releases  only  the	smtp_tls_mandatory_ciphers parameter is	imple-
       mented, and opportunistic TLS always uses "export" or better (i.e. all)
       ciphers.

smtp_tls_dcert_file (default: empty)
       File  with the Postfix SMTP client DSA certificate in PEM format.  This
       file may	also contain the Postfix SMTP client private DSA key.

       See the discussion under	smtp_tls_cert_file for more details.

       Example:

       smtp_tls_dcert_file = /etc/postfix/client-dsa.pem

       This feature is available in Postfix 2.2	and later.

smtp_tls_dkey_file (default: $smtp_tls_dcert_file)
       File with the Postfix SMTP client DSA private key in PEM	format.	  This
       file  may be combined with the Postfix SMTP client DSA certificate file
       specified with $smtp_tls_dcert_file.

       The private key must be accessible without a pass-phrase, i.e. it  must
       not be encrypted. File permissions should grant read-only access	to the
       system superuser	account	("root"), and no access	to anyone else.

       This feature is available in Postfix 2.2	and later.

smtp_tls_eccert_file (default: empty)
       File with the Postfix SMTP client  ECDSA	 certificate  in  PEM  format.
       This file may also contain the Postfix SMTP client ECDSA	private	key.

       See the discussion under	smtp_tls_cert_file for more details.

       Example:

       smtp_tls_eccert_file = /etc/postfix/ecdsa-ccert.pem

       This  feature  is  available  in	Postfix	2.6 and	later, when Postfix is
       compiled	and linked with	OpenSSL	1.0.0 or later.

smtp_tls_eckey_file (default: $smtp_tls_eccert_file)
       File with the Postfix SMTP client ECDSA	private	 key  in  PEM  format.
       This  file  may be combined with	the Postfix SMTP client	ECDSA certifi-
       cate file specified with	$smtp_tls_eccert_file.

       The private key must be accessible without a pass-phrase, i.e. it  must
       not be encrypted. File permissions should grant read-only access	to the
       system superuser	account	("root"), and no access	to anyone else.

       This feature is available in Postfix 2.6	and  later,  when  Postfix  is
       compiled	and linked with	OpenSSL	1.0.0 or later.

smtp_tls_enforce_peername (default: yes)
       With  mandatory	TLS  encryption,  require  that	the remote SMTP	server
       hostname	matches	the information	in the remote SMTP server certificate.
       As  of  RFC 2487	the requirements for hostname checking for MTA clients
       are not specified.

       This option can be set to "no" to disable strict	 peer  name  checking.
       This  setting  has  no  effect  on sessions that	are controlled via the
       smtp_tls_per_site table.

       Disabling the hostname verification can make sense in  closed  environ-
       ment where special CAs are created.  If not used	carefully, this	option
       opens the danger	of a "man-in-the-middle"  attack  (the	CommonName  of
       this attacker will be logged).

       This  feature  is  available in Postfix 2.2 and later. With Postfix 2.3
       and later use smtp_tls_security_level instead.

smtp_tls_exclude_ciphers (default: empty)
       List of ciphers or cipher types to exclude from the Postfix SMTP	client
       cipher  list  at	 all  TLS  security levels. This is not	an OpenSSL ci-
       pherlist, it is a simple	list separated by  whitespace  and/or  commas.
       The  elements  are a single cipher, or one or more "+" separated	cipher
       properties, in which case only ciphers matching all the properties  are
       excluded.

       Examples	(some of these will cause problems):

	   smtp_tls_exclude_ciphers = aNULL
	   smtp_tls_exclude_ciphers = MD5, DES
	   smtp_tls_exclude_ciphers = DES+MD5
	   smtp_tls_exclude_ciphers = AES256-SHA, DES-CBC3-MD5
	   smtp_tls_exclude_ciphers = kEDH+aRSA

       The  first  setting,  disables anonymous	ciphers. The next setting dis-
       ables ciphers that use the MD5 digest algorithm or the (single) DES en-
       cryption	 algorithm. The	next setting disables ciphers that use MD5 and
       DES together.  The next setting disables	the two	 ciphers  "AES256-SHA"
       and  "DES-CBC3-MD5".  The  last setting disables	ciphers	that use "EDH"
       key exchange with RSA authentication.

       This feature is available in Postfix 2.3	and later.

smtp_tls_fingerprint_cert_match	(default: empty)
       List of acceptable remote SMTP server certificate fingerprints for  the
       "fingerprint"  TLS  security  level  (smtp_tls_security_level = finger-
       print). At this security	level, certificate authorities are  not	 used,
       and  certificate	expiration times are ignored. Instead, server certifi-
       cates are verified directly via their "fingerprint". The	fingerprint is
       a message digest	of the server certificate. The digest algorithm	is se-
       lected via the smtp_tls_fingerprint_digest parameter.

       When an smtp_tls_policy_maps table entry	 specifies  the	 "fingerprint"
       security	 level,	 any "match" attributes	in that	entry specify the list
       of valid	fingerprints for the corresponding destination.	Multiple  fin-
       gerprints can be	combined with a	"|" delimiter in a single match	attri-
       bute, or	multiple match attributes can be employed.

       Example:	Certificate fingerprint	verification  with  internal  mailhub.
       Two  matching  fingerprints  are	 listed. The relayhost may be multiple
       physical	hosts behind a load-balancer, each with	its own	private/public
       key  and	self-signed certificate. Alternatively,	a single relayhost may
       be in the process of switching from one set of private/public  keys  to
       another,	and both keys are trusted just prior to	the transition.

	   relayhost = [mailhub.example.com]
	   smtp_tls_security_level = fingerprint
	   smtp_tls_fingerprint_digest = md5
	   smtp_tls_fingerprint_cert_match =
	       3D:95:34:51:24:66:33:B9:D2:40:99:C0:C1:17:0B:D1
	       EC:3B:2D:B0:5B:B1:FB:6D:20:A3:9D:72:F6:8D:12:35

       Example:	 Certificate  fingerprint  verification	with selected destina-
       tions.  As in the example above,	we show	two matching fingerprints:

	   /etc/postfix/main.cf:
	       smtp_tls_policy_maps = hash:/etc/postfix/tls_policy
	       smtp_tls_fingerprint_digest = md5

	   /etc/postfix/tls_policy:
	       example.com     fingerprint
		   match=3D:95:34:51:24:66:33:B9:D2:40:99:C0:C1:17:0B:D1
		   match=EC:3B:2D:B0:5B:B1:FB:6D:20:A3:9D:72:F6:8D:12:35

       This feature is available in Postfix 2.5	and later.

smtp_tls_fingerprint_digest (default: md5)
       The message digest algorithm used to construct remote SMTP server  cer-
       tificate	  fingerprints.	  At  the  "fingerprint"  TLS  security	 level
       (smtp_tls_security_level	= fingerprint),	the server certificate is ver-
       ified by	directly matching its fingerprint. The fingerprint is the mes-
       sage digest of the server certificate  using  the  selected  algorithm.
       With  a digest algorithm	resistant to "second pre-image"	attacks, it is
       not feasible to create a	new public key and a matching certificate that
       has the same fingerprint.

       The  default  algorithm	is  md5; this is consistent with the backwards
       compatible setting of the digest	used to	verify client certificates  in
       the SMTP	server.

       The  best practice algorithm is now sha1. Recent	advances in hash func-
       tion cryptanalysis have led to md5 being	deprecated in favor  of	 sha1.
       However,	 as  long  as  there  are  no known "second pre-image" attacks
       against md5, its	use in this context can	still be considered safe.

       While additional	digest algorithms are often available  with  OpenSSL's
       libcrypto, only those used by libssl in SSL cipher suites are available
       to Postfix. For now this	means just md5 or sha1.

       To find the fingerprint of a specific certificate file, with a specific
       digest algorithm, run:

	   $ openssl x509 -noout -fingerprint -digest -in certfile.pem

       The  text to the	right of "=" sign is the desired fingerprint.  For ex-
       ample:

	   $ openssl x509 -noout -fingerprint -sha1 -in	cert.pem
	   SHA1	Fingerprint=D4:6A:AB:19:24:79:F8:32:BB:A6:CB:66:82:C0:8E:9B:EE:29:A8:1A

       This feature is available in Postfix 2.5	and later.

smtp_tls_key_file (default: $smtp_tls_cert_file)
       File with the Postfix SMTP client RSA private key in PEM	format.	  This
       file  may be combined with the Postfix SMTP client RSA certificate file
       specified with $smtp_tls_cert_file.

       The private key must be accessible without a pass-phrase, i.e. it  must
       not be encrypted. File permissions should grant read-only access	to the
       system superuser	account	("root"), and no access	to anyone else.

       Example:

       smtp_tls_key_file = $smtp_tls_cert_file

       This feature is available in Postfix 2.2	and later.

smtp_tls_loglevel (default: 0)
       Enable additional Postfix SMTP client logging of	 TLS  activity.	  Each
       logging	level  also includes the information that is logged at a lower
       logging level.

	      0	Disable	logging	of TLS activity.

	      1	Log TLS	handshake and certificate information.

	      2	Log levels during TLS negotiation.

	      3	Log hexadecimal	and ASCII dump of TLS negotiation process.

	      4	Log hexadecimal	and ASCII dump of complete transmission	 after
	      STARTTLS.

       Use "smtp_tls_loglevel =	3" only	in case	of problems. Use of loglevel 4
       is strongly discouraged.

       This feature is available in Postfix 2.2	and later.

smtp_tls_mandatory_ciphers (default: medium)
       The minimum TLS cipher grade that the Postfix SMTP client will use with
       mandatory  TLS  encryption.  The	default	value "medium" is suitable for
       most destinations with which you	may want to enforce TLS, and is	beyond
       the  reach  of  today's cryptanalytic methods. See smtp_tls_policy_maps
       for information on how to configure ciphers on a	per-destination	basis.

       The following cipher grades are supported:

       export Enable "EXPORT" grade or better OpenSSL ciphers.	 This  is  the
	      default  for opportunistic encryption. It	is not recommended for
	      mandatory	encryption unless you must enforce TLS with "crippled"
	      peers.  The  underlying  cipherlist is specified via the tls_ex-
	      port_cipherlist configuration parameter, which you are  strongly
	      encouraged to not	change.

       low    Enable  "LOW"  grade or better OpenSSL ciphers.  This setting is
	      only appropriate for internal mail servers.  The underlying  ci-
	      pherlist	is  specified via the tls_low_cipherlist configuration
	      parameter, which you are strongly	encouraged to not change.

       medium Enable "MEDIUM" grade or better OpenSSL ciphers.	The underlying
	      cipherlist is specified via the tls_medium_cipherlist configura-
	      tion parameter, which you	are strongly encouraged	to not change.

       high   Enable only "HIGH" grade OpenSSL ciphers.	 This setting  may  be
	      appropriate  when	 all mandatory TLS destinations	(e.g. when all
	      mail is routed to	a suitably capable relayhost) support at least
	      one  "HIGH" grade	cipher.	The underlying cipherlist is specified
	      via the tls_high_cipherlist configuration	parameter,  which  you
	      are strongly encouraged to not change.

       null   Enable  only the "NULL" OpenSSL ciphers, these provide authenti-
	      cation without encryption.  This setting is only appropriate  in
	      the  rare	case that all servers are prepared to use NULL ciphers
	      (not normally enabled in TLS servers). A plausible  use-case  is
	      an LMTP server listening on a UNIX-domain	socket that is config-
	      ured to support "NULL" ciphers.  The  underlying	cipherlist  is
	      specified	 via  the tls_null_cipherlist configuration parameter,
	      which you	are strongly encouraged	to not change.

       The underlying cipherlists for grades other than	"null" include	anony-
       mous  ciphers,  but these are automatically filtered out	if the Postfix
       SMTP client is configured to verify server certificates.	 You are  very
       unlikely	 to  need to take any steps to exclude anonymous ciphers, they
       are excluded automatically as necessary.	 If you	must exclude anonymous
       ciphers	at  the	 "may"	or "encrypt" security levels, when the Postfix
       SMTP client does	not need or use	peer certificates,  set	 "smtp_tls_ex-
       clude_ciphers  =	 aNULL". To exclude anonymous ciphers only when	TLS is
       enforced, set "smtp_tls_mandatory_exclude_ciphers = aNULL".

       This feature is available in Postfix 2.3	and later.

smtp_tls_mandatory_exclude_ciphers (default: empty)
       Additional list of ciphers or cipher types to  exclude  from  the  SMTP
       client cipher list at mandatory TLS security levels. This list works in
       addition	to the exclusions listed  with	smtp_tls_exclude_ciphers  (see
       there for syntax	details).

       Starting	with Postfix 2.6, the mandatory	cipher exclusions can be spec-
       ified on	a per-destination basis	via the	TLS  policy  "exclude"	attri-
       bute. See smtp_tls_policy_maps for notes	and examples.

       This feature is available in Postfix 2.3	and later.

smtp_tls_mandatory_protocols (default: !SSLv2)
       List  of	 SSL/TLS  protocols that the Postfix SMTP client will use with
       mandatory TLS encryption.  In  main.cf  the  values  are	 separated  by
       whitespace, commas or colons. In	the policy table "protocols" attribute
       (see smtp_tls_policy_maps) the only valid separator is colon. An	 empty
       value  means allow all protocols. The valid protocol names, (see	\fBfB-
       SSL_get_version(3)), are	"SSLv2", "SSLv3" and "TLSv1".

       Note: As	of OpenSSL 1.0.1 two new protocols are defined,	"TLSv1.1"  and
       "TLSv1.2".  If an older Postfix version is linked against OpenSSL 1.0.1
       or later, these,	or any other new protocol versions,  are  uncondition-
       ally enabled.

       With  Postfix >=	2.5 the	parameter syntax is expanded to	support	proto-
       col exclusions.	One  can  now  explicitly  exclude  SSLv2  by  setting
       "smtp_tls_mandatory_protocols  =	 !SSLv2".  To  exclude	both SSLv2 and
       SSLv3 set "smtp_tls_mandatory_protocols = !SSLv2, !SSLv3". Listing  the
       protocols  to  include, rather than protocols to	exclude, is supported,
       but not recommended. The	exclusion form more closely matches the	behav-
       iour when the OpenSSL library is	newer than Postfix.

       Since  SSL  version  2  has known protocol weaknesses and is now	depre-
       cated, the default setting excludes "SSLv2".  This means	 that  by  de-
       fault,  SSL  version 2 will not be used at the "encrypt"	security level
       and higher.

       See  the	 documentation	of  the	 smtp_tls_policy_maps  parameter   and
       TLS_README for more information about security levels.

       Example:

       # Preferred form	with Postfix >=	2.5:
       smtp_tls_mandatory_protocols = !SSLv2, !SSLv3
       # Alternative form.
       smtp_tls_mandatory_protocols = TLSv1

       This feature is available in Postfix 2.3	and later.

smtp_tls_note_starttls_offer (default: no)
       Log the hostname	of a remote SMTP server	that offers STARTTLS, when TLS
       is not already enabled for that server.

       The logfile record looks	like:

       postfix/smtp[pid]:  Host	offered	STARTTLS: [name.of.host]

       This feature is available in Postfix 2.2	and later.

smtp_tls_per_site (default: empty)
       Optional	lookup tables with the Postfix SMTP client TLS usage policy by
       next-hop	 destination  and  by  remote SMTP server hostname.  When both
       lookups succeed,	the more specific per-site policy  (NONE,  MUST,  etc)
       overrides  the  less  specific  one (MAY), and the more secure per-site
       policy (MUST, etc) overrides the	less secure one	(NONE).	 With  Postfix
       2.3   and   later   smtp_tls_per_site   is  strongly  discouraged:  use
       smtp_tls_policy_maps instead.

       Use of the bare hostname	as the per-site	table lookup key  is  discour-
       aged.  Always  use  the full destination	nexthop	(enclosed in []	with a
       possible	":port"	suffix). A recipient domain  or	 MX-enabled  transport
       next-hop	 with  no  port	 suffix	 may look like a bare hostname,	but is
       still a suitable	destination.

       Specify a next-hop destination or  server  hostname  on	the  left-hand
       side;  no wildcards are allowed.	The next-hop destination is either the
       recipient domain, or the	destination specified with a transport(5)  ta-
       ble, the	relayhost parameter, or	the relay_transport parameter.	On the
       right hand side specify one of the following keywords:

       NONE   Don't use	TLS at all. This overrides a less specific MAY	lookup
	      result from the alternate	host or	next-hop lookup	key, and over-
	      rides   the   global   smtp_use_tls,    smtp_enforce_tls,	   and
	      smtp_tls_enforce_peername	settings.

       MAY    Try  to  use  TLS	if the server announces	support, otherwise use
	      the unencrypted connection. This has less	precedence than	a more
	      specific	result	(including  NONE)  from	 the alternate host or
	      next-hop lookup key, and has less	precedence than	the more  spe-
	      cific global "smtp_enforce_tls = yes" or "smtp_tls_enforce_peer-
	      name = yes".

       MUST_NOPEERMATCH
	      Require TLS encryption, but do not require that the remote  SMTP
	      server  hostname	matches	 the  information  in  the remote SMTP
	      server certificate, or that the server certificate was issued by
	      a	 trusted  CA. This overrides a less secure NONE	or a less spe-
	      cific MAY	lookup result from  the	 alternate  host  or  next-hop
	      lookup  key,  and	 overrides  the	 global	smtp_use_tls, smtp_en-
	      force_tls	and smtp_tls_enforce_peername settings.

       MUST   Require TLS encryption, require  that  the  remote  SMTP	server
	      hostname	matches	the information	in the remote SMTP server cer-
	      tificate,	and require that the remote  SMTP  server  certificate
	      was  issued  by  a trusted CA. This overrides a less secure NONE
	      and MUST_NOPEERMATCH or a	less specific MAY lookup  result  from
	      the  alternate  host  or	next-hop lookup	key, and overrides the
	      global smtp_use_tls, smtp_enforce_tls and	smtp_tls_enforce_peer-
	      name settings.

       The above keywords correspond to	the "none", "may", "encrypt" and "ver-
       ify" security levels for	the new	smtp_tls_security_level	parameter  in-
       troduced	 in  Postfix 2.3. Starting with	Postfix	2.3, and independently
       of how the policy  is  specified,  the  smtp_tls_mandatory_ciphers  and
       smtp_tls_mandatory_protocols  parameters	 apply	when TLS encryption is
       mandatory. Connections for which	encryption is optional	typically  en-
       able  all  "export"  grade and better ciphers (see smtp_tls_ciphers and
       smtp_tls_protocols).

       As long as no secure DNS	lookup mechanism is available, false hostnames
       in  MX  or  CNAME responses can change the server hostname that Postfix
       uses for	TLS policy lookup and server  certificate  verification.  Even
       with  a	perfect	 match between the server hostname and the server cer-
       tificate, there is no guarantee that Postfix is connected to the	 right
       server.	 See TLS_README	(Closing a DNS loophole	with obsolete per-site
       TLS policies) for a possible work-around.

       This feature is available in Postfix 2.2	and later.  With  Postfix  2.3
       and later use smtp_tls_policy_maps instead.

smtp_tls_policy_maps (default: empty)
       Optional	lookup tables with the Postfix SMTP client TLS security	policy
       by next-hop destination;	when a	non-empty  value  is  specified,  this
       overrides the obsolete smtp_tls_per_site	parameter.  See	TLS_README for
       a more detailed discussion of TLS security levels.

       The TLS policy table is indexed by the full next-hop destination, which
       is  either  the recipient domain, or the	verbatim next-hop specified in
       the  transport  table,	$local_transport,   $virtual_transport,	  $re-
       lay_transport or	$default_transport. This includes any enclosing	square
       brackets	and any	non-default destination	server port suffix.  The  LMTP
       socket type prefix (inet: or unix:) is not included in the lookup key.

       Only  the  next-hop  domain,  or	$myhostname with LMTP over UNIX-domain
       sockets,	is used	as the nexthop name for	certificate verification.  The
       port  and  any  enclosing  square brackets are used in the table	lookup
       key, but	are not	used for server	name verification.

       When the	lookup key is a	domain name without enclosing square  brackets
       or  any :port suffix (typically the recipient domain), and the full do-
       main is not found in the	table, just as with  the  transport(5)	table,
       the  parent  domain starting with a leading "." is matched recursively.
       This allows one to specify a security policy for	a recipient domain and
       all its sub-domains.

       The  lookup result is a security	level, followed	by an optional list of
       whitespace and/or comma separated name=value attributes	that  override
       related	main.cf	settings. The TLS security levels in order of increas-
       ing security are:

       none   No TLS. No additional attributes are supported at	this level.

       may    Opportunistic TLS. Since sending in the clear is acceptable, de-
	      manding stronger than default TLS	security merely	reduces	inter-
	      operability. The optional	"ciphers", "exclude"  and  "protocols"
	      attributes (available for	opportunistic TLS with Postfix >= 2.6)
	      override the "smtp_tls_ciphers", "smtp_tls_exclude_ciphers"  and
	      "smtp_tls_protocols"  configuration parameters. When opportunis-
	      tic TLS handshakes fail, Postfix retries the connection with TLS
	      disabled.	  This allows mail delivery to sites with non-interop-
	      erable TLS implementations.

       encrypt
	      Mandatory	TLS encryption.	At this	level and higher, the optional
	      "protocols"  attribute  overrides	 the  main.cf  smtp_tls_manda-
	      tory_protocols parameter,	the optional "ciphers" attribute over-
	      rides  the main.cf smtp_tls_mandatory_ciphers parameter, and the
	      optional "exclude" attribute  (Postfix  >=  2.6)	overrides  the
	      main.cf  smtp_tls_mandatory_exclude_ciphers  parameter.  In  the
	      policy table, multiple protocols or  excluded  ciphers  must  be
	      separated	 by colons, as attribute values	may not	contain	white-
	      space or commas.

       fingerprint
	      Certificate fingerprint verification. Available with Postfix 2.5
	      and later. At this security level, there are no trusted certifi-
	      cate authorities.	The certificate	trust chain, expiration	 date,
	      ...  are	not checked. Instead, the optional match attribute, or
	      else  the	 main.cf  smtp_tls_fingerprint_cert_match   parameter,
	      lists  the  valid	 "fingerprints"	of the server certificate. The
	      digest algorithm used to calculate the fingerprint  is  selected
	      by  the  smtp_tls_fingerprint_digest parameter. Multiple finger-
	      prints can be combined with a "|"	delimiter in  a	 single	 match
	      attribute, or multiple match attributes can be employed. The ":"
	      character	is not used as a delimiter as it occurs	 between  each
	      pair of fingerprint (hexadecimal)	digits.

       verify Mandatory	 TLS  verification.   At  this	security level,	DNS MX
	      lookups are trusted to be	secure enough, and the	name  verified
	      in  the  server  certificate  is usually obtained	indirectly via
	      unauthenticated DNS MX lookups.  The optional "match"  attribute
	      overrides	 the  main.cf smtp_tls_verify_cert_match parameter. In
	      the policy table,	multiple match patterns	and strategies must be
	      separated	by colons.  In practice	explicit control over matching
	      is more common with the "secure" policy, described below.

       secure Secure-channel TLS. At this  security  level,  DNS  MX  lookups,
	      though  potentially  used	 to  determine	the candidate next-hop
	      gateway IP addresses, are	not trusted to be  secure  enough  for
	      TLS peername verification. Instead, the default name verified in
	      the server certificate is	obtained directly from	the  next-hop,
	      or  is  explicitly  specified  via  the optional match attribute
	      which overrides the main.cf  smtp_tls_secure_cert_match  parame-
	      ter. In the policy table,	multiple match patterns	and strategies
	      must be separated	by colons.  The	match attribute	is most	useful
	      when multiple domains are	supported by common server, the	policy
	      entries for additional domains specify matching  rules  for  the
	      primary  domain  certificate.  While  transport  table overrides
	      routing the secondary domains to the primary nexthop also	 allow
	      secure verification, they	risk delivery to the wrong destination
	      when domains change hands	or are re-assigned  to	new  gateways.
	      With  the	 "match" attribute approach, routing is	not perturbed,
	      and mail is deferred if verification of a	new MX host fails.

       Example:

       /etc/postfix/main.cf:
	   smtp_tls_policy_maps	= hash:/etc/postfix/tls_policy
	   # Postfix 2.5 and later
	   smtp_tls_fingerprint_digest = md5

       /etc/postfix/tls_policy:
	   example.edu		       none
	   example.mil		       may
	   example.gov		       encrypt protocols=TLSv1
	   example.com		       verify ciphers=high
	   example.net		       secure
	   .example.net		       secure match=.example.net:example.net
	   [mail.example.org]:587      secure match=nexthop
	   # Postfix 2.5 and later
	   [thumb.example.org]		fingerprint
	    match=EC:3B:2D:B0:5B:B1:FB:6D:20:A3:9D:72:F6:8D:12:35
	    match=3D:95:34:51:24:66:33:B9:D2:40:99:C0:C1:17:0B:D1

       Note: The hostname strategy if  listed  in  a  non-default  setting  of
       smtp_tls_secure_cert_match  or in the match attribute in	the policy ta-
       ble can render the secure level vulnerable to DNS forgery. Do  not  use
       the hostname strategy for secure-channel	configurations in environments
       where DNS security is not assured.

       This feature is available in Postfix 2.3	and later.

smtp_tls_protocols (default: !SSLv2)
       List of TLS protocols that the Postfix SMTP client will exclude or  in-
       clude with opportunistic	TLS encryption.	Starting with Postfix 2.6, the
       Postfix SMTP client will	by default not use the obsolete	 SSLv2	proto-
       col.

       In main.cf the values are separated by whitespace, commas or colons. In
       the policy table	(see smtp_tls_policy_maps) the only valid separator is
       colon.  An  empty  value	 means allow all protocols. The	valid protocol
       names, (see \fBfBSSL_get_version(3)), are "SSLv2", "SSLv3" and "TLSv1".

       Note: As	of OpenSSL 1.0.1 two new protocols are defined,	"TLSv1.1"  and
       "TLSv1.2".  If an older Postfix version is linked against OpenSSL 1.0.1
       or later, these,	or any other new protocol versions,  are  uncondition-
       ally enabled.

       To  include  a  protocol	 list its name,	to exclude it, prefix the name
       with a "!" character. To	exclude	SSLv2 even for opportunistic  TLS  set
       "smtp_tls_protocols  = !SSLv2". To exclude both "SSLv2" and "SSLv3" set
       "smtp_tls_protocols = !SSLv2, !SSLv3". Explicitly listing the protocols
       to  include,  rather  than  protocols to	exclude, is supported, but not
       recommended.  The exclusion form	more  closely  matches	the  behaviour
       when the	OpenSSL	library	is newer than Postfix.

       Example:
       # TLSv1 only!
       smtp_tls_protocols = !SSLv2, !SSLv3

       This feature is available in Postfix 2.6	and later.

smtp_tls_scert_verifydepth (default: 9)
       The  verification depth for remote SMTP server certificates. A depth of
       1 is sufficient if the issuing CA is listed in a	local CA file.

       The default verification	depth is 9 (the	OpenSSL	default) for  compati-
       bility with earlier Postfix behavior. Prior to Postfix 2.5, the default
       value was 5, but	the limit was not actually enforced. If	you  have  set
       this  to	 a  lower  non-default	value,	certificates with longer trust
       chains may now fail to verify. Certificate chains with 1	or 2  CAs  are
       common,	deeper	chains	are  more  rare	and any	number between 5 and 9
       should suffice in practice. You can choose a lower number if, for exam-
       ple,  you  trust	 certificates directly signed by an issuing CA but not
       any CAs it delegates to.

       This feature is available in Postfix 2.2	and later.

smtp_tls_secure_cert_match (default: nexthop, dot-nexthop)
       The server certificate peername verification method  for	 the  "secure"
       TLS  security  level.  In  a  "secure" TLS policy table ($smtp_tls_pol-
       icy_maps) entry the optional "match" attribute overrides	 this  main.cf
       setting.

       This  parameter	specifies one or more patterns or strategies separated
       by commas, whitespace or	colons.	 In the	policy table  the  only	 valid
       separator is the	colon character.

       For   a	description  of	 the  pattern  and  strategy  syntax  see  the
       smtp_tls_verify_cert_match parameter. The "hostname" strategy should be
       avoided	in this	context, as in the absence of a	secure global DNS, us-
       ing the results of MX lookups in	certificate verification is not	immune
       to active (man-in-the-middle) attacks on	DNS.

       Sample main.cf setting:

	   smtp_tls_secure_cert_match =	nexthop

       Sample policy table override:

	   example.net	   secure match=example.com:.example.com
	   .example.net	   secure match=example.com:.example.com

       This feature is available in Postfix 2.3	and later.

smtp_tls_security_level	(default: empty)
       The default SMTP	TLS security level for the Postfix SMTP	client;	when a
       non-empty value is specified, this overrides  the  obsolete  parameters
       smtp_use_tls, smtp_enforce_tls, and smtp_tls_enforce_peername.

       Specify one of the following security levels:

       none   TLS  will	 not  be used unless enabled for specific destinations
	      via smtp_tls_policy_maps.

       may    Opportunistic TLS. Use TLS if this is supported  by  the	remote
	      SMTP server, otherwise use plaintext. Since sending in the clear
	      is acceptable, demanding	stronger  than	default	 TLS  security
	      merely  reduces  inter-operability.   The	"smtp_tls_ciphers" and
	      "smtp_tls_protocols" (Postfix >= 2.6)  configuration  parameters
	      provide  control	over  the protocols and	cipher grade used with
	      opportunistic TLS.  With earlier releases	the opportunistic  TLS
	      cipher  grade  is	always "export"	and no protocols are disabled.
	      When TLS handshakes fail,	the connection	is  retried  with  TLS
	      disabled.	  This allows mail delivery to sites with non-interop-
	      erable TLS implementations.

       encrypt
	      Mandatory	TLS encryption.	Since a	minimum	level of  security  is
	      intended,	it is reasonable to be specific	about sufficiently se-
	      cure protocol versions and ciphers. At this security  level  and
	      higher,  the main.cf parameters smtp_tls_mandatory_protocols and
	      smtp_tls_mandatory_ciphers specify the TLS protocols and minimum
	      cipher grade which the administrator considers secure enough for
	      mandatory	encrypted sessions. This security level	is not an  ap-
	      propriate	default	for systems delivering mail to the Internet.

       fingerprint
	      Certificate fingerprint verification. Available with Postfix 2.5
	      and later. At this security level, there are no trusted certifi-
	      cate  authorities. The certificate trust chain, expiration date,
	      ...   are	  not	checked.   Instead,    the    smtp_tls_finger-
	      print_cert_match parameter lists the valid "fingerprints"	of the
	      server certificate. The digest algorithm used to	calculate  the
	      fingerprint  is  selected	by the smtp_tls_fingerprint_digest pa-
	      rameter.

       verify Mandatory	TLS verification.  At  this  security  level,  DNS  MX
	      lookups  are  trusted to be secure enough, and the name verified
	      in the server certificate	is  usually  obtained  indirectly  via
	      unauthenticated  DNS  MX lookups.	The smtp_tls_verify_cert_match
	      parameter	controls how the server	name is	verified. In  practice
	      explicit	control	 over  matching	is more	common at the "secure"
	      level, described below. This security level is not an  appropri-
	      ate default for systems delivering mail to the Internet.

       secure Secure-channel  TLS.   At	 this  security	level, DNS MX lookups,
	      though potentially used  to  determine  the  candidate  next-hop
	      gateway  IP  addresses,  are not trusted to be secure enough for
	      TLS peername verification. Instead, the default name verified in
	      the  server  certificate is obtained from	the next-hop domain as
	      specified	in the smtp_tls_secure_cert_match configuration	param-
	      eter.  The  default  matching  rule is that a server certificate
	      matches when its name is equal to	or is a	sub-domain of the nex-
	      thop  domain.  This security level is not	an appropriate default
	      for systems delivering mail to the Internet.

       Examples:

       # No TLS. Formerly: smtp_use_tls=no and smtp_enforce_tls=no.
       smtp_tls_security_level = none

       # Opportunistic TLS.
       smtp_tls_security_level = may
       # Postfix >= 2.6:
       # Do not	tweak opportunistic ciphers or protocol	unless it is essential
       # to do so (if a	security vulnerability is found	in the SSL library that
       # can be	mitigated by disabling a particular protocol or	raising	the
       # cipher	grade from "export" to "low" or	"medium").
       smtp_tls_ciphers	= export
       smtp_tls_protocols = !SSLv2

       # Mandatory (high-grade)	TLS encryption.
       smtp_tls_security_level = encrypt
       smtp_tls_mandatory_ciphers = high

       # Mandatory TLS verification of hostname	or nexthop domain.
       smtp_tls_security_level = verify
       smtp_tls_mandatory_ciphers = high
       smtp_tls_verify_cert_match = hostname, nexthop, dot-nexthop

       # Secure	channel	TLS with exact nexthop name match.
       smtp_tls_security_level = secure
       smtp_tls_mandatory_protocols = TLSv1
       smtp_tls_mandatory_ciphers = high
       smtp_tls_secure_cert_match = nexthop

       # Certificate fingerprint verification (Postfix >= 2.5).
       # The CA-less "fingerprint" security level only scales to a limited
       # number	of destinations. As a global default rather than a per-site
       # setting, this is practical when mail for all recipients is sent
       # to a central mail hub.
       relayhost = [mailhub.example.com]
       smtp_tls_security_level = fingerprint
       smtp_tls_mandatory_protocols = !SSLv2, !SSLv3
       smtp_tls_mandatory_ciphers = high
       smtp_tls_fingerprint_cert_match =
	   3D:95:34:51:24:66:33:B9:D2:40:99:C0:C1:17:0B:D1
	   EC:3B:2D:B0:5B:B1:FB:6D:20:A3:9D:72:F6:8D:12:35

       This feature is available in Postfix 2.3	and later.

smtp_tls_session_cache_database	(default: empty)
       Name of the file	containing the optional	Postfix	SMTP client  TLS  ses-
       sion  cache. Specify a database type that supports enumeration, such as
       btree or	sdbm; there is no need to support concurrent access.  The file
       is  created  if it does not exist. The smtp(8) daemon does not use this
       parameter directly, rather the cache is implemented indirectly  in  the
       tlsmgr(8) daemon. This means that per-smtp-instance master.cf overrides
       of this parameter are not effective.  Note,  that  each	of  the	 cache
       databases supported by tlsmgr(8)	daemon:	$smtpd_tls_session_cache_data-
       base, $smtp_tls_session_cache_database (and with	Postfix	2.3 and	 later
       $lmtp_tls_session_cache_database), needs	to be stored separately. It is
       not at this time	possible to store multiple caches in  a	 single	 data-
       base.

       Note:  dbm  databases  are  not	suitable.  TLS session objects are too
       large.

       As of version 2.5, Postfix no longer uses root privileges when  opening
       this  file.  The	 file  should  now  be	stored under the Postfix-owned
       data_directory. As a migration aid, an attempt to open the file under a
       non-Postfix  directory  is  redirected to the Postfix-owned data_direc-
       tory, and a warning is logged.

       Example:

       smtp_tls_session_cache_database = btree:/var/db/postfix/smtp_scache

       This feature is available in Postfix 2.2	and later.

smtp_tls_session_cache_timeout (default: 3600s)
       The expiration time of Postfix SMTP client TLS session  cache  informa-
       tion.   A  cache	cleanup	is performed periodically every	$smtp_tls_ses-
       sion_cache_timeout seconds. As  with  $smtp_tls_session_cache_database,
       this  parameter	is  implemented	 in the	tlsmgr(8) daemon and therefore
       per-smtp-instance master.cf overrides are not possible.

       This feature is available in Postfix 2.2	and later.

smtp_tls_verify_cert_match (default: hostname)
       The server certificate peername verification method  for	 the  "verify"
       TLS  security  level.  In  a  "verify" TLS policy table ($smtp_tls_pol-
       icy_maps) entry the optional "match" attribute overrides	 this  main.cf
       setting.

       This  parameter	specifies one or more patterns or strategies separated
       by commas, whitespace or	colons.	 In the	policy table  the  only	 valid
       separator is the	colon character.

       Patterns	specify	domain names, or domain	name suffixes:

       example.com
	      Match  the  example.com domain, i.e. one of the names the	server
	      certificate must be example.com, upper and lower	case  distinc-
	      tions are	ignored.

       .example.com
	      Match subdomains of the example.com domain, i.e. match a name in
	      the server certificate that consists of a	non-zero number	of la-
	      bels  followed  by  a .example.com suffix. Case distinctions are
	      ignored.

       Strategies specify a transformation from	the next-hop domain to the ex-
       pected name in the server certificate:

       nexthop
	      Match against the	next-hop domain, which is either the recipient
	      domain, or the transport	next-hop  configured  for  the	domain
	      stripped	of  any	 optional socket type prefix, enclosing	square
	      brackets and trailing port. When MX lookups are not  suppressed,
	      this  is the original nexthop domain prior to the	MX lookup, not
	      the result of the	MX lookup. For LMTP delivery  via  UNIX-domain
	      sockets, the verified next-hop name is $myhostname.  This	strat-
	      egy is suitable for use with the "secure"	policy.	 Case  is  ig-
	      nored.

       dot-nexthop
	      As above,	but match server certificate names that	are subdomains
	      of the next-hop domain. Case is ignored.

       hostname
	      Match against the	hostname of the	server,	often obtained via  an
	      unauthenticated DNS MX lookup. For LMTP delivery via UNIX-domain
	      sockets, the verified name is $myhostname. This matches the ver-
	      ification	 strategy  of  the  "MUST"  keyword  in	 the  obsolete
	      smtp_tls_per_site	table, and is suitable for use with the	 "ver-
	      ify"  security  level.  When  the	 next-hop  name	is enclosed in
	      square brackets to suppress MX lookups, the "hostname"  strategy
	      is the same as the "nexthop" strategy. Case is ignored.

       Sample main.cf setting:

       smtp_tls_verify_cert_match = hostname, nexthop, dot-nexthop

       Sample policy table override:

       example.com     verify  match=hostname:nexthop
       .example.com    verify  match=example.com:.example.com:hostname

       This feature is available in Postfix 2.3	and later.

smtp_use_tls (default: no)
       Opportunistic  mode: use	TLS when a remote SMTP server announces	START-
       TLS support, otherwise send the mail in the clear.  Beware:  some  SMTP
       servers	offer  STARTTLS	 even if it is not configured.	With Postfix <
       2.3, if the TLS handshake fails,	and no other server is available,  de-
       livery  is  deferred  and mail stays in the queue. If this is a concern
       for you,	use the	smtp_tls_per_site feature instead.

       This feature is available in Postfix 2.2	and later.  With  Postfix  2.3
       and later use smtp_tls_security_level instead.

smtp_xforward_timeout (default:	300s)
       The  SMTP  client  time limit for sending the XFORWARD command, and for
       receiving the server response.

       Time units: s (seconds),	m (minutes), h (hours),	d (days),  w  (weeks).
       The default time	unit is	s (seconds).

       This feature is available in Postfix 2.1	and later.

smtpd_authorized_verp_clients (default:	$authorized_verp_clients)
       What  SMTP clients are allowed to specify the XVERP command.  This com-
       mand requests that mail be delivered one	recipient at a time with a per
       recipient return	address.

       By default, no clients are allowed to specify XVERP.

       This  parameter was renamed with	Postfix	version	2.1. The default value
       is backwards compatible with Postfix version 2.0.

       Specify a list of network/netmask patterns, separated by	commas	and/or
       whitespace.  The	 mask specifies	the number of bits in the network part
       of a host address. You can also specify hostnames or .domain names (the
       initial	 dot   causes	the  domain  to	 match	any  name  below  it),
       "/file/name" or "type:table" patterns.  A "/file/name" pattern  is  re-
       placed  by  its contents; a "type:table"	lookup table is	matched	when a
       table entry matches a lookup string (the	 lookup	 result	 is  ignored).
       Continue	 long lines by starting	the next line with whitespace. Specify
       "!pattern" to exclude an	address	or network block from  the  list.  The
       form "!/file/name" is supported only in Postfix version 2.4 and later.

       Note:  IP  version 6 address information	must be	specified inside [] in
       the smtpd_authorized_verp_clients value,	and in	files  specified  with
       "/file/name".   IP  version  6 addresses	contain	the ":"	character, and
       would otherwise be confused with	a "type:table" pattern.

smtpd_authorized_xclient_hosts (default: empty)
       What SMTP clients are allowed to	use the	XCLIENT	feature.  This command
       overrides SMTP client information that is used for access control. Typ-
       ical use	is for SMTP-based content filters, fetchmail-like programs, or
       SMTP  server  access  rule testing. See the XCLIENT_README document for
       details.

       This feature is available in Postfix 2.1	and later.

       By default, no clients are allowed to specify XCLIENT.

       Specify a list of network/netmask patterns, separated by	commas	and/or
       whitespace.  The	 mask specifies	the number of bits in the network part
       of a host address. You can also specify hostnames or .domain names (the
       initial	 dot   causes	the  domain  to	 match	any  name  below  it),
       "/file/name" or "type:table" patterns.  A "/file/name" pattern  is  re-
       placed  by  its contents; a "type:table"	lookup table is	matched	when a
       table entry matches a lookup string (the	 lookup	 result	 is  ignored).
       Continue	 long lines by starting	the next line with whitespace. Specify
       "!pattern" to exclude an	address	or network block from  the  list.  The
       form "!/file/name" is supported only in Postfix version 2.4 and later.

       Note:  IP  version 6 address information	must be	specified inside [] in
       the smtpd_authorized_xclient_hosts value, and in	files  specified  with
       "/file/name".   IP  version  6 addresses	contain	the ":"	character, and
       would otherwise be confused with	a "type:table" pattern.

smtpd_authorized_xforward_hosts	(default: empty)
       What SMTP clients are allowed to	use the	XFORWARD feature.   This  com-
       mand  forwards  information that	is used	to improve logging after SMTP-
       based content filters. See the XFORWARD_README document for details.

       This feature is available in Postfix 2.1	and later.

       By default, no clients are allowed to specify XFORWARD.

       Specify a list of network/netmask patterns, separated by	commas	and/or
       whitespace.  The	 mask specifies	the number of bits in the network part
       of a host address. You can also specify hostnames or .domain names (the
       initial	 dot   causes	the  domain  to	 match	any  name  below  it),
       "/file/name" or "type:table" patterns.  A "/file/name" pattern  is  re-
       placed  by  its contents; a "type:table"	lookup table is	matched	when a
       table entry matches a lookup string (the	 lookup	 result	 is  ignored).
       Continue	 long lines by starting	the next line with whitespace. Specify
       "!pattern" to exclude an	address	or network block from  the  list.  The
       form "!/file/name" is supported only in Postfix version 2.4 and later.

       Note:  IP  version 6 address information	must be	specified inside [] in
       the smtpd_authorized_xforward_hosts value, and in files specified  with
       "/file/name".   IP  version  6 addresses	contain	the ":"	character, and
       would otherwise be confused with	a "type:table" pattern.

smtpd_banner (default: $myhostname ESMTP $mail_name)
       The text	that follows the 220 status code in the	SMTP greeting  banner.
       Some  people like to see	the mail version advertised. By	default, Post-
       fix shows no version.

       You MUST	specify	$myhostname at the start of the	text. This is required
       by the SMTP protocol.

       Example:

       smtpd_banner = $myhostname ESMTP	$mail_name ($mail_version)

smtpd_client_connection_count_limit (default: 50)
       How many	simultaneous connections any client is allowed to make to this
       service.	 By default, the limit is set  to  half	 the  default  process
       limit value.

       To disable this feature,	specify	a limit	of 0.

       WARNING:	 The purpose of	this feature is	to limit abuse.	It must	not be
       used to regulate	legitimate mail	traffic.

       This feature is available in Postfix 2.2	and later.

smtpd_client_connection_rate_limit (default: 0)
       The maximal number of connection	attempts any client is allowed to make
       to  this	 service  per  time unit.  The time unit is specified with the
       anvil_rate_time_unit configuration parameter.

       By default, a client can	make as	many  connections  per	time  unit  as
       Postfix can accept.

       To disable this feature,	specify	a limit	of 0.

       WARNING:	 The purpose of	this feature is	to limit abuse.	It must	not be
       used to regulate	legitimate mail	traffic.

       This feature is available in Postfix 2.2	and later.

       Example:

       smtpd_client_connection_rate_limit = 1000

smtpd_client_event_limit_exceptions (default: $mynetworks)
       Clients that are	excluded from smtpd_client_*_count/rate_limit restric-
       tions. See the mynetworks parameter description for the parameter value
       syntax.

       By default, clients in trusted networks are excluded. Specify a list of
       network	blocks,	hostnames or .domain names (the	initial	dot causes the
       domain to match any name	below it).

       Note: IP	version	6 address information must be specified	inside	[]  in
       the  smtpd_client_event_limit_exceptions	 value,	and in files specified
       with "/file/name".  IP version 6	addresses contain the  ":"  character,
       and would otherwise be confused with a "type:table" pattern.

       This feature is available in Postfix 2.2	and later.

smtpd_client_message_rate_limit	(default: 0)
       The  maximal number of message delivery requests	that any client	is al-
       lowed to	make to	this service per time unit, regardless of  whether  or
       not  Postfix  actually accepts those messages.  The time	unit is	speci-
       fied with the anvil_rate_time_unit configuration	parameter.

       By default, a client can	send as	many  message  delivery	 requests  per
       time unit as Postfix can	accept.

       To disable this feature,	specify	a limit	of 0.

       WARNING:	 The purpose of	this feature is	to limit abuse.	It must	not be
       used to regulate	legitimate mail	traffic.

       This feature is available in Postfix 2.2	and later.

       Example:

       smtpd_client_message_rate_limit = 1000

smtpd_client_new_tls_session_rate_limit	(default: 0)
       The maximal number of new (i.e.,	uncached) TLS sessions that  a	remote
       SMTP  client  is	 allowed to negotiate with this	service	per time unit.
       The time	unit is	specified with the anvil_rate_time_unit	 configuration
       parameter.

       By default, a remote SMTP client	can negotiate as many new TLS sessions
       per time	unit as	Postfix	can accept.

       To disable this feature,	specify	a limit	of  0.	Otherwise,  specify  a
       limit that is at	least the per-client concurrent	session	limit, or else
       legitimate client sessions may be rejected.

       WARNING:	The purpose of this feature is to limit	abuse. It must not  be
       used to regulate	legitimate mail	traffic.

       This feature is available in Postfix 2.3	and later.

       Example:

       smtpd_client_new_tls_session_rate_limit = 100

smtpd_client_port_logging (default: no)
       Enable  logging of the remote SMTP client port in addition to the host-
       name and	IP address. The	logging	format is "host[address]:port".

       This feature is available in Postfix 2.5	and later.

smtpd_client_recipient_rate_limit (default: 0)
       The maximal number of recipient addresses that any client is allowed to
       send  to	this service per time unit, regardless of whether or not Post-
       fix actually accepts those recipients.  The time	unit is	specified with
       the anvil_rate_time_unit	configuration parameter.

       By default, a client can	send as	many recipient addresses per time unit
       as Postfix can accept.

       To disable this feature,	specify	a limit	of 0.

       WARNING:	The purpose of this feature is to limit	abuse. It must not  be
       used to regulate	legitimate mail	traffic.

       This feature is available in Postfix 2.2	and later.

       Example:

       smtpd_client_recipient_rate_limit = 1000

smtpd_client_restrictions (default: empty)
       Optional	 SMTP  server  access  restrictions in the context of a	client
       SMTP connection request.	  See  SMTPD_ACCESS_README,  section  "Delayed
       evaluation of SMTP access restriction lists" for	a discussion of	evalu-
       ation context and time.

       The default is to allow all connection requests.

       Specify a list of restrictions, separated by commas and/or  whitespace.
       Continue	 long  lines  by  starting the next line with whitespace.  Re-
       strictions are applied in the order as specified; the first restriction
       that matches wins.

       The  following  restrictions  are specific to client hostname or	client
       network address information.

       check_ccert_access type:table
	      Use the client certificate fingerprint as	 lookup	 key  for  the
	      specified	access(5) database; with Postfix version 2.2, also re-
	      quire that the SMTP client certificate is	verified successfully.
	      The   fingerprint	 digest	 algorithm  is	configurable  via  the
	      smtpd_tls_fingerprint_digest parameter (hard-coded as md5	 prior
	      to Postfix version 2.5).	This feature is	available with Postfix
	      version 2.2 and later.

       check_client_access type:table
	      Search the specified access database for	the  client  hostname,
	      parent  domains,	client	IP  address,  or  networks obtained by
	      stripping	least significant octets.  See	the  access(5)	manual
	      page for details.

       check_client_mx_access type:table
	      Search the specified access(5) database for the MX hosts for the
	      client hostname, and execute the corresponding action.  Note:  a
	      result  of  "OK" is not allowed for safety reasons. Instead, use
	      DUNNO in order to	exclude	specific hosts from blacklists.	  This
	      feature is available in Postfix 2.7 and later.

       check_client_ns_access type:table
	      Search  the specified access(5) database for the DNS servers for
	      the client  hostname,  and  execute  the	corresponding  action.
	      Note:  a	result	of "OK"	is not allowed for safety reasons. In-
	      stead, use DUNNO in order	to exclude specific hosts from	black-
	      lists.  This feature is available	in Postfix 2.7 and later.

       check_reverse_client_hostname_access type:table
	      Search  the specified access database for	the unverified reverse
	      client hostname, parent domains, client IP address, or  networks
	      obtained	by  stripping  least  significant  octets. See the ac-
	      cess(5) manual page for details.	Note: a	result of "OK" is  not
	      allowed  for safety reasons.  Instead, use DUNNO in order	to ex-
	      clude specific hosts from	blacklists.  This feature is available
	      in Postfix 2.6 and later.

       check_reverse_client_hostname_mx_access type:table
	      Search the specified access(5) database for the MX hosts for the
	      unverified reverse client	hostname, and execute the  correspond-
	      ing  action.   Note:  a result of	"OK" is	not allowed for	safety
	      reasons.	Instead, use DUNNO in order to exclude specific	 hosts
	      from  blacklists.	  This feature is available in Postfix 2.7 and
	      later.

       check_reverse_client_hostname_ns_access type:table
	      Search the specified access(5) database for the DNS servers  for
	      the  unverified  reverse client hostname,	and execute the	corre-
	      sponding action.	Note: a	result of  "OK"	 is  not  allowed  for
	      safety reasons.  Instead,	use DUNNO in order to exclude specific
	      hosts from blacklists.  This feature is available	in Postfix 2.7
	      and later.

       permit_inet_interfaces
	      Permit  the request when the client IP address matches $inet_in-
	      terfaces.

       permit_mynetworks
	      Permit the request when the client IP address matches  any  net-
	      work or network address listed in	 $mynetworks.

       permit_sasl_authenticated
	      Permit the request when the client is successfully authenticated
	      via the RFC 4954 (AUTH) protocol.

       permit_tls_all_clientcerts
	      Permit the request when the remote SMTP  client  certificate  is
	      verified	successfully.  This option must	be used	only if	a spe-
	      cial CA issues the certificates and only this CA	is  listed  as
	      trusted  CA.  Otherwise,	clients	with a third-party certificate
	      would also be allowed to relay.  Specify	"tls_append_default_CA
	      =	 no" when the trusted CA is specified with smtpd_tls_CAfile or
	      smtpd_tls_CApath,	to prevent Postfix from	appending the  system-
	      supplied	default	 CAs.	This feature is	available with Postfix
	      version 2.2.

       permit_tls_clientcerts
	      Permit the request when the remote SMTP client certificate  fin-
	      gerprint	is  listed in $relay_clientcerts.  The fingerprint di-
	      gest algorithm is	configurable via the smtpd_tls_fingerprint_di-
	      gest parameter (hard-coded as md5	prior to Postfix version 2.5).
	      This feature is available	with Postfix version 2.2.

       reject_rbl_client rbl_domain=d.d.d.d
	      Reject the request when the reversed client network  address  is
	      listed  with  the	 A  record "d.d.d.d" under rbl_domain (Postfix
	      version 2.1 and later only).  Each "d" is	a number, or a pattern
	      inside  "[]"  that contains one or more ";"-separated numbers or
	      number..number ranges (Postfix version 2.8 and  later).	If  no
	      "=d.d.d.d"  is  specified,  reject the request when the reversed
	      client network address is	listed with any	A record under rbl_do-
	      main.
	      The  maps_rbl_reject_code	 parameter specifies the response code
	      for rejected requests  (default:	 554),	the  default_rbl_reply
	      parameter	 specifies  the	 default server	reply, and the rbl_re-
	      ply_maps	parameter specifies tables with	server replies indexed
	      by  rbl_domain.	This  feature  is available in Postfix 2.0 and
	      later.

       permit_dnswl_client dnswl_domain=d.d.d.d
	      Accept the request when the reversed client network  address  is
	      listed with the A	record "d.d.d.d" under dnswl_domain.  Each "d"
	      is a number, or a	pattern	inside "[]" that contains one or  more
	      ";"-separated   numbers	or   number..number   ranges.	If  no
	      "=d.d.d.d" is specified, accept the request  when	 the  reversed
	      client  network  address	is  listed  with  any  A  record under
	      dnswl_domain.
	      For safety, permit_dnswl_client  is  silently  ignored  when  it
	      would  override  reject_unauth_destination.   The	 result	is DE-
	      FER_IF_REJECT when whitelist  lookup  fails.   This  feature  is
	      available	in Postfix 2.8 and later.

       reject_rhsbl_client rbl_domain=d.d.d.d
	      Reject the request when the client hostname is listed with the A
	      record "d.d.d.d" under rbl_domain	(Postfix version 2.1 and later
	      only).  Each "d" is a number, or a pattern inside	"[]" that con-
	      tains one	or more	";"-separated numbers or number..number	ranges
	      (Postfix version 2.8 and later).	If no "=d.d.d.d" is specified,
	      reject the request when the client hostname is listed with any A
	      record  under  rbl_domain. See the reject_rbl_client description
	      above for	additional RBL related configuration parameters.  This
	      feature is available in Postfix 2.0 and later; with Postfix ver-
	      sion 2.8 and  later,  reject_rhsbl_reverse_client	 will  usually
	      produce better results.

       permit_rhswl_client rhswl_domain=d.d.d.d
	      Accept the request when the client hostname is listed with the A
	      record "d.d.d.d" under rhswl_domain.  Each "d" is	a number, or a
	      pattern inside "[]" that contains	one or more ";"-separated num-
	      bers or number..number ranges. If	no  "=d.d.d.d"	is  specified,
	      accept the request when the client hostname is listed with any A
	      record under rhswl_domain.
	      Caution: client name whitelisting	is fragile, since  the	client
	      name  lookup  can	 fail  due  to temporary outages.  Client name
	      whitelisting should be used only to reduce  false	 positives  in
	      e.g.   DNS-based	blocklists, and	not for	making access rule ex-
	      ceptions.
	      For safety, permit_rhswl_client  is  silently  ignored  when  it
	      would  override  reject_unauth_destination.   The	 result	is DE-
	      FER_IF_REJECT when whitelist  lookup  fails.   This  feature  is
	      available	in Postfix 2.8 and later.

       reject_rhsbl_reverse_client rbl_domain=d.d.d.d
	      Reject  the  request when	the unverified reverse client hostname
	      is listed	with the A record "d.d.d.d"  under  rbl_domain.	  Each
	      "d"  is  a number, or a pattern inside "[]" that contains	one or
	      more ";"-separated numbers  or  number..number  ranges.	If  no
	      "=d.d.d.d"  is specified,	reject the request when	the unverified
	      reverse client hostname  is  listed  with	 any  A	 record	 under
	      rbl_domain.  See the reject_rbl_client description above for ad-
	      ditional RBL related configuration parameters.  This feature  is
	      available	in Postfix 2.8 and later.

       reject_unknown_client_hostname	(with	Postfix	  <   2.3:  reject_un-
       known_client)
	      Reject the request when 1) the client IP	address->name  mapping
	      fails,  2)  the name->address mapping fails, or 3) the name->ad-
	      dress mapping does not match the client IP address.
	      This is  a  stronger  restriction	 than  the  reject_unknown_re-
	      verse_client_hostname  feature, which triggers only under	condi-
	      tion 1) above.
	      The unknown_client_reject_code parameter specifies the  response
	      code  for	 rejected requests (default: 450). The reply is	always
	      450 in case the address->name or name->address lookup failed due
	      to a temporary problem.

       reject_unknown_reverse_client_hostname
	      Reject  the  request  when  the  client  IP  address  has	no ad-
	      dress->name mapping.
	      This   is	  a   weaker   restriction   than    the    reject_un-
	      known_client_hostname  feature, which requires not only that the
	      address->name and	name->address mappings exist,  but  also  that
	      the two mappings reproduce the client IP address.
	      The  unknown_client_reject_code parameter	specifies the response
	      code for rejected	requests (default: 450).  The reply is	always
	      450  in  case the	address->name lookup failed due	to a temporary
	      problem.
	      This feature is available	in Postfix 2.3 and later.

       In addition, you	can use	any of	the  following	generic	 restrictions.
       These restrictions are applicable in any	SMTP command context.

       check_policy_service servername
	      Query  the  specified policy server. See the SMTPD_POLICY_README
	      document for details. This feature is available in  Postfix  2.1
	      and later.

       defer  Defer  the  request. The client is told to try again later. This
	      restriction is useful at the end of a restriction	list, to  make
	      the default policy explicit.
	      The  defer_code  parameter  specifies the	SMTP server reply code
	      (default:	450).

       defer_if_permit
	      Defer the	request	if some	later restriction would	result	in  an
	      explicit	or  implicit  PERMIT  action.	This  is useful	when a
	      blacklisting feature fails due to	 a  temporary  problem.	  This
	      feature is available in Postfix version 2.1 and later.

       defer_if_reject
	      Defer  the  request  if some later restriction would result in a
	      REJECT action.  This is useful when a whitelisting feature fails
	      due  to a	temporary problem.  This feature is available in Post-
	      fix version 2.1 and later.

       permit Permit the request. This restriction is useful at	the end	 of  a
	      restriction list,	to make	the default policy explicit.

       reject_multi_recipient_bounce
	      Reject the request when the envelope sender is the null address,
	      and the message has multiple envelope recipients.	This usage has
	      rare  but	 legitimate  applications:  under  certain conditions,
	      multi-recipient mail that	was posted with	 the  DSN  option  NO-
	      TIFY=NEVER may be	forwarded with the null	sender address.
	      Note:  this  restriction	can  only  work	 reliably when used in
	      smtpd_data_restrictions or  smtpd_end_of_data_restrictions,  be-
	      cause  the total number of recipients is not known at an earlier
	      stage of the SMTP	conversation.  Use at the RCPT stage will only
	      reject the second	etc.  recipient.
	      The  multi_recipient_bounce_reject_code  parameter specifies the
	      response code for	rejected requests (default:  550).  This  fea-
	      ture is available	in Postfix 2.1 and later.

       reject_plaintext_session
	      Reject  the  request  when the connection	is not encrypted. This
	      restriction should not be	used  before  the  client  has	had  a
	      chance  to  negotiate  encryption	with the AUTH or STARTTLS com-
	      mands.
	      The plaintext_reject_code	parameter specifies the	response  code
	      for  rejected  requests (default:	 450).	This feature is	avail-
	      able in Postfix 2.3 and later.

       reject_unauth_pipelining
	      Reject the request when the client sends SMTP commands ahead  of
	      time where it is not allowed, or when the	client sends SMTP com-
	      mands ahead of time without knowing that Postfix	actually  sup-
	      ports  ESMTP  command pipelining.	This stops mail	from bulk mail
	      software that improperly uses ESMTP command pipelining in	 order
	      to speed up deliveries.
	      With  Postfix  2.6 and later, the	SMTP server sets a per-session
	      flag whenever it detects illegal pipelining, including pipelined
	      EHLO or HELO commands. The reject_unauth_pipelining feature sim-
	      ply tests	whether	the flag was set at any	point in  time	during
	      the session.
	      With older Postfix versions, reject_unauth_pipelining checks the
	      current status of	the input read queue, and  its	usage  is  not
	      recommended in contexts other than smtpd_data_restrictions.

       reject Reject  the  request. This restriction is	useful at the end of a
	      restriction list,	to make	the default policy explicit.  The  re-
	      ject_code	 configuration	parameter  specifies the response code
	      for rejected requests (default: 554).

       sleep seconds
	      Pause for	the specified number of	seconds	and proceed  with  the
	      next  restriction	in the list, if	any. This may stop zombie mail
	      when used	as:
	      /etc/postfix/main.cf:
		  smtpd_client_restrictions =
		      sleep 1, reject_unauth_pipelining
		  smtpd_delay_reject = no
	      This feature is available	in Postfix 2.3.

       warn_if_reject
	      Change the meaning of the	next restriction, so that  it  logs  a
	      warning instead of rejecting a request (look for logfile records
	      that contain "reject_warning"). This is useful for  testing  new
	      restrictions in a	"live" environment without risking unnecessary
	      loss of mail.

       Other restrictions that are valid in this context:

       o      SMTP command specific restrictions that are described under  the
	      smtpd_helo_restrictions,	smtpd_sender_restrictions or smtpd_re-
	      cipient_restrictions parameters. When helo, sender or  recipient
	      restrictions  are	 listed	 under smtpd_client_restrictions, they
	      have effect  only	 with  "smtpd_delay_reject  =  yes",  so  that
	      $smtpd_client_restrictions  is evaluated at the time of the RCPT
	      TO command.

       Example:

       smtpd_client_restrictions = permit_mynetworks, reject_unknown_client_hostname

smtpd_command_filter (default: empty)
       A mechanism to transform	commands from remote SMTP clients.  This is  a
       last-resort  tool to work around	client commands	that break inter-oper-
       ability with the	Postfix	SMTP server.  Other uses involve fault	injec-
       tion to test Postfix's handling of invalid commands.

       Specify	the  name of a "type:table" lookup table. The search string is
       the SMTP	command	as received from the remote SMTP client,  except  that
       initial	whitespace  and	the trailing <CR><LF> are removed.  The	result
       value is	executed by the	Postfix	SMTP server.

       There is	no need	to use smtpd_command_filter for	the following cases:

       o      Use "resolve_numeric_domain = yes" to accept "user@ipaddress".

       o      Postfix already accepts the correct form "user@[ipaddress]". Use
	      virtual_alias_maps or canonical_maps to translate	these into do-
	      main names if necessary.

       o      Use "strict_rfc821_envelopes = no" to accept "RCPT TO:<User Name
	      _user@example.com__".  Postfix  will ignore the "User Name" part
	      and deliver to the _user@example.com_ address.

       Examples	of problems that can be	solved with  the  smtpd_command_filter
       feature:

       /etc/postfix/main.cf:
	   smtpd_command_filter	= pcre:/etc/postfix/command_filter

       /etc/postfix/command_filter:
	   # Work around clients that send malformed HELO commands.
	   /^HELO\s*$/ HELO domain.invalid

	   # Work around clients that send empty lines.
	   /^\s*$/     NOOP

	   # Work around clients that send RCPT	TO:<'user@domain'>.
	   # WARNING: do not lose the parameters that follow the address.
	   /^RCPT\s+TO:\s*<'([^[:space:]]+)'>(.*)/     RCPT TO:<$1>$2

	   # Bounce-never mail sink. Use notify_classes=bounce,resource,software
	   # to	send bounced mail to the postmaster (with message body removed).
	   /^(RCPT\s+TO:.*?)\bNOTIFY=\S+\b(.*)/	$1 NOTIFY=NEVER	$2
	   /^(RCPT\s+TO:.*)/			$1 NOTIFY=NEVER

       This feature is available in Postfix 2.7.

smtpd_data_restrictions	(default: empty)
       Optional	 access	 restrictions  that the	Postfix	SMTP server applies in
       the context of the SMTP DATA command.  See SMTPD_ACCESS_README, section
       "Delayed	 evaluation of SMTP access restriction lists" for a discussion
       of evaluation context and time.

       This feature is available in Postfix 2.0	and later.

       Specify a list of restrictions, separated by commas and/or  whitespace.
       Continue	 long  lines  by  starting the next line with whitespace.  Re-
       strictions are applied in the order as specified; the first restriction
       that matches wins.

       The following restrictions are valid in this context:

       o      Generic  restrictions  that can be used in any SMTP command con-
	      text, described under smtpd_client_restrictions.

       o      SMTP   command	specific    restrictions    described	 under
	      smtpd_client_restrictions,	      smtpd_helo_restrictions,
	      smtpd_sender_restrictions	or smtpd_recipient_restrictions.

       o      However, no recipient information	is available in	 the  case  of
	      multi-recipient mail. Acting on only one recipient would be mis-
	      leading,	because	 any  decision	will  affect  all   recipients
	      equally.	Acting on all recipients would require a possibly very
	      large amount of memory, and would	also  be  misleading  for  the
	      reasons mentioned	before.

       Examples:

       smtpd_data_restrictions = reject_unauth_pipelining
       smtpd_data_restrictions = reject_multi_recipient_bounce

smtpd_delay_open_until_valid_rcpt (default: yes)
       Postpone	 the  start  of	an SMTP	mail transaction until a valid RCPT TO
       command is received. Specify "no" to create a mail transaction as  soon
       as the SMTP server receives a valid MAIL	FROM command.

       With  sites  that  reject lots of mail, the default setting reduces the
       use of disk, CPU	and memory resources. The downside  is	that  rejected
       recipients  are	logged	with NOQUEUE instead of	a mail transaction ID.
       This complicates	the logfile analysis of	multi-recipient	mail.

       This feature is available in Postfix 2.3	and later.

smtpd_delay_reject (default: yes)
       Wait until the RCPT TO command before evaluating	$smtpd_client_restric-
       tions, $smtpd_helo_restrictions and $smtpd_sender_restrictions, or wait
       until the ETRN command before evaluating	$smtpd_client_restrictions and
       $smtpd_helo_restrictions.

       This  feature  is  turned on by default because some clients apparently
       mis-behave when the Postfix SMTP	server rejects	commands  before  RCPT
       TO.

       The default setting has one major benefit: it allows Postfix to log re-
       cipient address information when	rejecting  a  client  name/address  or
       sender  address,	so that	it is possible to find out whose mail is being
       rejected.

smtpd_discard_ehlo_keyword_address_maps	(default: empty)
       Lookup tables, indexed by the remote SMTP client	address, with case in-
       sensitive  lists	 of  EHLO  keywords (pipelining, starttls, auth, etc.)
       that the	SMTP server will not send in the EHLO  response	 to  a	remote
       SMTP client. See	smtpd_discard_ehlo_keywords for	details.  The table is
       not searched by hostname	for robustness reasons.

       This feature is available in Postfix 2.2	and later.

smtpd_discard_ehlo_keywords (default: empty)
       A case insensitive list of EHLO keywords	(pipelining,  starttls,	 auth,
       etc.)  that the SMTP server will	not send in the	EHLO response to a re-
       mote SMTP client.

       This feature is available in Postfix 2.2	and later.

       Notes:

       o      Specify the silent-discard pseudo	keyword	to prevent this	action
	      from being logged.

       o      Use  the smtpd_discard_ehlo_keyword_address_maps feature to dis-
	      card EHLO	keywords selectively.

smtpd_end_of_data_restrictions (default: empty)
       Optional	access restrictions that the Postfix SMTP  server  applies  in
       the  context of the SMTP	END-OF-DATA command.  See SMTPD_ACCESS_README,
       section "Delayed	evaluation of SMTP access  restriction	lists"	for  a
       discussion of evaluation	context	and time.

       This feature is available in Postfix 2.2	and later.

       See smtpd_data_restrictions for details and limitations.

smtpd_enforce_tls (default: no)
       Mandatory  TLS:	announce STARTTLS support to SMTP clients, and require
       that clients use	TLS encryption.	 According to RFC 2487 this  MUST  NOT
       be  applied  in case of a publicly-referenced SMTP server.  This	option
       is off by default and should be used only on dedicated servers.

       Note 1: "smtpd_enforce_tls = yes" implies "smtpd_tls_auth_only =	yes".

       Note 2: when invoked via	 "sendmail  -bs",  Postfix  will  never	 offer
       STARTTLS	 due  to  insufficient privileges to access the	server private
       key. This is intended behavior.

       This feature is available in Postfix 2.2	and later.  With  Postfix  2.3
       and later use smtpd_tls_security_level instead.

smtpd_error_sleep_time (default: 1s)
       With  Postfix version 2.1 and later: the	SMTP server response delay af-
       ter a client has	made more  than	 $smtpd_soft_error_limit  errors,  and
       fewer than $smtpd_hard_error_limit errors, without delivering mail.

       With  Postfix  version  2.0  and	 earlier: the SMTP server delay	before
       sending a reject	(4xx or	5xx) response, when the	client has made	 fewer
       than $smtpd_soft_error_limit errors without delivering mail.

smtpd_etrn_restrictions	(default: empty)
       Optional	 SMTP  server  access  restrictions in the context of a	client
       ETRN request.  See SMTPD_ACCESS_README, section "Delayed	evaluation  of
       SMTP  access  restriction lists"	for a discussion of evaluation context
       and time.

       The Postfix ETRN	implementation accepts only destinations that are eli-
       gible  for  the	Postfix	"fast flush" service. See the ETRN_README file
       for details.

       Specify a list of restrictions, separated by commas and/or  whitespace.
       Continue	 long  lines  by  starting the next line with whitespace.  Re-
       strictions are applied in the order as specified; the first restriction
       that matches wins.

       The  following restrictions are specific	to the domain name information
       received	with the ETRN command.

       check_etrn_access type:table
	      Search the specified access database for the ETRN	domain name or
	      its parent domains. See the access(5) manual page	for details.

       Other restrictions that are valid in this context:

       o      Generic  restrictions  that can be used in any SMTP command con-
	      text, described under smtpd_client_restrictions.

       o      SMTP   command	specific    restrictions    described	 under
	      smtpd_client_restrictions	and smtpd_helo_restrictions.

       Example:

       smtpd_etrn_restrictions = permit_mynetworks, reject

smtpd_expansion_filter (default: see postconf -d output)
       What characters are allowed in $name expansions of RBL reply templates.
       Characters not in the allowed set are replaced by "_".  Use C like  es-
       capes to	specify	special	characters such	as whitespace.

       This parameter is not subjected to $parameter expansion.

       This feature is available in Postfix 2.0	and later.

smtpd_forbidden_commands (default: CONNECT, GET, POST)
       List of commands	that cause the Postfix SMTP server to immediately ter-
       minate the session with a 221 code. This	 can  be  used	to  disconnect
       clients	that obviously attempt to abuse	the system. In addition	to the
       commands	listed in this parameter, commands that	 follow	 the  "Label:"
       format of message headers will also cause a disconnect.

       This feature is available in Postfix 2.2	and later.

smtpd_hard_error_limit (default: normal: 20, overload: 1)
       The  maximal  number  of	errors a remote	SMTP client is allowed to make
       without delivering mail.	The Postfix SMTP server	disconnects  when  the
       limit is	exceeded. Normally the default limit is	20, but	it changes un-
       der overload to just 1. With Postfix 2.5	and earlier, the  SMTP	server
       always allows up	to 20 errors by	default.

smtpd_helo_required (default: no)
       Require	that  a	 remote	SMTP client introduces itself with the HELO or
       EHLO command before sending the MAIL command or other commands that re-
       quire EHLO negotiation.

       Example:

       smtpd_helo_required = yes

smtpd_helo_restrictions	(default: empty)
       Optional	 restrictions that the Postfix SMTP server applies in the con-
       text of the SMTP	HELO command.  See SMTPD_ACCESS_README,	 section  "De-
       layed  evaluation of SMTP access	restriction lists" for a discussion of
       evaluation context and time.

       The default is to permit	everything.

       Note: specify "smtpd_helo_required = yes" to  fully  enforce  this  re-
       striction  (without  "smtpd_helo_required  =  yes", a client can	simply
       skip smtpd_helo_restrictions by not sending HELO	or EHLO).

       Specify a list of restrictions, separated by commas and/or  whitespace.
       Continue	 long  lines  by  starting the next line with whitespace.  Re-
       strictions are applied in the order as specified; the first restriction
       that matches wins.

       The following restrictions are specific to the hostname information re-
       ceived with the HELO or EHLO command.

       check_helo_access type:table
	      Search the specified access(5) database for  the	HELO  or  EHLO
	      hostname	or  parent  domains, and execute the corresponding ac-
	      tion.  Note: specify "smtpd_helo_required	= yes"	to  fully  en-
	      force  this  restriction (without	"smtpd_helo_required = yes", a
	      client can simply	skip check_helo_access by not sending HELO  or
	      EHLO).

       check_helo_mx_access type:table
	      Search the specified access(5) database for the MX hosts for the
	      HELO or EHLO hostname, and  execute  the	corresponding  action.
	      Note  1: a result	of "OK"	is not allowed for safety reasons. In-
	      stead, use DUNNO in order	to exclude specific hosts from	black-
	      lists.  Note 2: specify "smtpd_helo_required = yes" to fully en-
	      force this restriction (without "smtpd_helo_required =  yes",  a
	      client  can simply skip check_helo_mx_access by not sending HELO
	      or EHLO).	 This feature is available in Postfix 2.1 and later.

       check_helo_ns_access type:table
	      Search the specified access(5) database for the DNS servers  for
	      the HELO or EHLO hostname, and execute the corresponding action.
	      Note 1: a	result of "OK" is not allowed for safety reasons.  In-
	      stead,  use DUNNO	in order to exclude specific hosts from	black-
	      lists.  Note 2: specify "smtpd_helo_required = yes" to fully en-
	      force  this  restriction (without	"smtpd_helo_required = yes", a
	      client can simply	skip check_helo_ns_access by not sending  HELO
	      or EHLO).	This feature is	available in Postfix 2.1 and later.

       reject_invalid_helo_hostname  (with Postfix < 2.3: reject_invalid_host-
       name)
	      Reject the request when the HELO or EHLO hostname	syntax is  in-
	      valid.  Note:  specify  "smtpd_helo_required = yes" to fully en-
	      force this restriction (without "smtpd_helo_required =  yes",  a
	      client can simply	skip reject_invalid_helo_hostname by not send-
	      ing HELO or EHLO).
	      The invalid_hostname_reject_code specifies the response code for
	      rejected requests	(default: 501).

       reject_non_fqdn_helo_hostname	 (with	   Postfix    <	   2.3:	   re-
       ject_non_fqdn_hostname)
	      Reject the request when the HELO or  EHLO	 hostname  is  not  in
	      fully-qualified domain form, as required by the RFC. Note: spec-
	      ify "smtpd_helo_required = yes" to fully enforce	this  restric-
	      tion  (without  "smtpd_helo_required = yes", a client can	simply
	      skip reject_non_fqdn_helo_hostname by not	sending	HELO or	EHLO).
	      The non_fqdn_reject_code parameter specifies the	response  code
	      for rejected requests (default: 504).

       reject_rhsbl_helo rbl_domain=d.d.d.d
	      Reject  the  request  when the HELO or EHLO hostname hostname is
	      listed with the A	record	"d.d.d.d"  under  rbl_domain  (Postfix
	      version 2.1 and later only).  Each "d" is	a number, or a pattern
	      inside "[]" that contains	one or more ";"-separated  numbers  or
	      number..number  ranges  (Postfix	version	2.8 and	later).	 If no
	      "=d.d.d.d" is specified, reject the request  when	 the  HELO  or
	      EHLO  hostname is	listed with any	A record under rbl_domain. See
	      the reject_rbl_client description	 for  additional  RBL  related
	      configuration  parameters.  Note:	specify	"smtpd_helo_required =
	      yes" to fully enforce this restriction (without  "smtpd_helo_re-
	      quired = yes", a client can simply skip reject_rhsbl_helo	by not
	      sending HELO or EHLO). This feature is available in Postfix  2.0
	      and later.

       reject_unknown_helo_hostname  (with Postfix < 2.3: reject_unknown_host-
       name)
	      Reject the request when the HELO or EHLO hostname	has no	DNS  A
	      or MX record.
	      The unknown_hostname_reject_code parameter specifies the numeri-
	      cal response code	for rejected requests (default:	450).
	      The  unknown_helo_hostname_tempfail_action  parameter  specifies
	      the  action  after a temporary DNS error (default: defer_if_per-
	      mit). Note: specify "smtpd_helo_required = yes" to fully enforce
	      this  restriction	(without "smtpd_helo_required =	yes", a	client
	      can simply skip reject_unknown_helo_hostname by not sending HELO
	      or EHLO).

       Other restrictions that are valid in this context:

       o      Generic  restrictions  that can be used in any SMTP command con-
	      text, described under smtpd_client_restrictions.

       o      Client hostname or network  address  specific  restrictions  de-
	      scribed under smtpd_client_restrictions.

       o      SMTP    command	 specific    restrictions    described	 under
	      smtpd_sender_restrictions	or smtpd_recipient_restrictions.  When
	      sender or	recipient restrictions are listed under	smtpd_helo_re-
	      strictions, they have effect  only  with	"smtpd_delay_reject  =
	      yes",  so	that $smtpd_helo_restrictions is evaluated at the time
	      of the RCPT TO command.

       Examples:

       smtpd_helo_restrictions = permit_mynetworks, reject_invalid_helo_hostname
       smtpd_helo_restrictions = permit_mynetworks, reject_unknown_helo_hostname

smtpd_history_flush_threshold (default:	100)
       The maximal number of lines in the Postfix SMTP server command  history
       before it is flushed upon receipt of EHLO, RSET,	or end of DATA.

smtpd_junk_command_limit (default: normal: 100,	overload: 1)
       The  number  of	junk commands (NOOP, VRFY, ETRN	or RSET) that a	remote
       SMTP client can send before the Postfix SMTP server starts to increment
       the  error  counter  with each junk command.  The junk command count is
       reset after mail	is delivered.  See also	the smtpd_error_sleep_time and
       smtpd_soft_error_limit  configuration parameters.  Normally the default
       limit is	100, but it changes under overload to just 1. With Postfix 2.5
       and  earlier,  the SMTP server always allows up to 100 junk commands by
       default.

smtpd_milters (default:	empty)
       A list of Milter	(mail filter) applications for new mail	 that  arrives
       via  the	 Postfix  smtpd(8) server.  See	the MILTER_README document for
       details.

       This feature is available in Postfix 2.3	and later.

smtpd_noop_commands (default: empty)
       List of commands	that the Postfix SMTP server replies to	with "250 Ok",
       without	doing any syntax checks	and without changing state.  This list
       overrides any commands built into the Postfix SMTP server.

smtpd_null_access_lookup_key (default: <>)
       The lookup key to be used in SMTP access(5) tables instead of the  null
       sender address.

smtpd_peername_lookup (default:	yes)
       Attempt to look up the remote SMTP client hostname, and verify that the
       name matches the	client IP address. A client name is set	 to  "unknown"
       when  it	 cannot	 be looked up or verified, or when name	lookup is dis-
       abled.  Turning off name	lookup reduces delays due to  DNS  lookup  and
       increases the maximal inbound delivery rate.

       This feature is available in Postfix 2.3	and later.

smtpd_policy_service_max_idle (default:	300s)
       The time	after which an idle SMTPD policy service connection is closed.

       This feature is available in Postfix 2.1	and later.

smtpd_policy_service_max_ttl (default: 1000s)
       The  time  after	 which	an  active  SMTPD policy service connection is
       closed.

       This feature is available in Postfix 2.1	and later.

smtpd_policy_service_timeout (default: 100s)
       The time	limit for connecting to, writing to or receiving from a	 dele-
       gated SMTPD policy server.

       This feature is available in Postfix 2.1	and later.

smtpd_proxy_ehlo (default: $myhostname)
       How  the	 Postfix SMTP server announces itself to the proxy filter.  By
       default,	the Postfix hostname is	used.

       This feature is available in Postfix 2.1	and later.

smtpd_proxy_filter (default: empty)
       The hostname and	TCP port of the	 mail  filtering  proxy	 server.   The
       proxy  receives	all mail from the Postfix SMTP server, and is supposed
       to give the result to another Postfix SMTP server process.

       Specify	"host:port"  or	 "inet:host:port"  for	a  TCP	endpoint,   or
       "unix:pathname"	for  a UNIX-domain endpoint. The host can be specified
       as an IP	address	or as a	symbolic name; no MX lookups are  done.	  When
       no  "host"  or  "host:"	 are  specified, the local machine is assumed.
       Pathname	interpretation is relative to the Postfix queue	directory.

       This feature is available in Postfix 2.1	and later.

       The "inet:" and "unix:" prefixes	 are  available	 in  Postfix  2.3  and
       later.

smtpd_proxy_options (default: empty)
       List  of	 options that control how the Postfix SMTP server communicates
       with a before-queue content filter. Specify zero	or more	of the follow-
       ing, separated by comma or whitespace.

       speed_adjust
	      Do  not connect to a before-queue	content	filter until an	entire
	      message has been received. This reduces the number of simultane-
	      ous before-queue content filter processes.

       NOTE  1:	A filter must not selectively reject recipients	of a multi-re-
       cipient message.	 Rejecting all recipients is OK, as is	accepting  all
       recipients.

       NOTE  2:	 This feature increases	the minimum amount of free queue space
       by $message_size_limit. The extra space is needed to save  the  message
       to a temporary file.

       This feature is available in Postfix 2.7	and later.

smtpd_proxy_timeout (default: 100s)
       The  time limit for connecting to a proxy filter	and for	sending	or re-
       ceiving information.  When a connection fails the client	gets a generic
       error  message while more detailed information is logged	to the maillog
       file.

       Time units: s (seconds),	m (minutes), h (hours),	d (days),  w  (weeks).
       The default time	unit is	s (seconds).

       This feature is available in Postfix 2.1	and later.

smtpd_recipient_limit (default:	1000)
       The  maximal  number of recipients that the Postfix SMTP	server accepts
       per message delivery request.

smtpd_recipient_overshoot_limit	(default: 1000)
       The number of recipients	that a remote SMTP client can send  in	excess
       of  the limit specified with $smtpd_recipient_limit, before the Postfix
       SMTP server increments the per-session error count for each excess  re-
       cipient.

smtpd_recipient_restrictions (default: permit_mynetworks, reject_unauth_desti-
       nation)
       The access restrictions that the	Postfix	SMTP  server  applies  in  the
       context	of the RCPT TO command.	 See SMTPD_ACCESS_README, section "De-
       layed evaluation	of SMTP	access restriction lists" for a	discussion  of
       evaluation context and time.

       By default, the Postfix SMTP server accepts:

       o      Mail from	clients	whose IP address matches $mynetworks, or:

       o      Mail  to	remote	destinations that match	$relay_domains,	except
	      for addresses that contain sender-specified routing  (user@else-
	      where@domain), or:

       o      Mail  to	local  destinations  that  match  $inet_interfaces  or
	      $proxy_interfaces,  $mydestination,  $virtual_alias_domains,  or
	      $virtual_mailbox_domains.

       IMPORTANT:  If  you  change this	parameter setting, you must specify at
       least one of the	following restrictions.	Otherwise Postfix will	refuse
       to receive mail:

	   reject, defer, defer_if_permit, reject_unauth_destination

       Specify	a list of restrictions,	separated by commas and/or whitespace.
       Continue	long lines by starting the next	 line  with  whitespace.   Re-
       strictions are applied in the order as specified; the first restriction
       that matches wins.

       The following restrictions are specific to the recipient	 address  that
       is received with	the RCPT TO command.

       check_recipient_access type:table
	      Search the specified access(5) database for the resolved RCPT TO
	      address, domain, parent domains, or localpart@, and execute  the
	      corresponding action.

       check_recipient_mx_access type:table
	      Search the specified access(5) database for the MX hosts for the
	      RCPT TO domain, and execute the corresponding action.   Note:  a
	      result  of  "OK" is not allowed for safety reasons. Instead, use
	      DUNNO in order to	exclude	specific hosts from blacklists.	  This
	      feature is available in Postfix 2.1 and later.

       check_recipient_ns_access type:table
	      Search  the specified access(5) database for the DNS servers for
	      the RCPT TO domain, and execute the corresponding	action.	 Note:
	      a	result of "OK" is not allowed for safety reasons. Instead, use
	      DUNNO in order to	exclude	specific hosts from blacklists.	  This
	      feature is available in Postfix 2.1 and later.

       permit_auth_destination
	      Permit the request when one of the following is true:

       o      Postfix  is  mail	forwarder: the resolved	RCPT TO	domain matches
	      $relay_domains or	a subdomain thereof, and the address  contains
	      no sender-specified routing (user@elsewhere@domain),

       o      Postfix  is  the	final destination: the resolved	RCPT TO	domain
	      matches  $mydestination,	$inet_interfaces,   $proxy_interfaces,
	      $virtual_alias_domains, or $virtual_mailbox_domains, and the ad-
	      dress contains no	sender-specified  routing  (user@elsewhere@do-
	      main).

       permit_mx_backup
	      Permit  the  request when	the local mail system is backup	MX for
	      the RCPT TO domain, or when the domain is	an authorized destina-
	      tion (see	permit_auth_destination	for definition).

       o      Safety:  permit_mx_backup	 does  not  accept addresses that have
	      sender-specified	routing	  information	(example:   user@else-
	      where@domain).

       o      Safety:  permit_mx_backup	 can be	vulnerable to mis-use when ac-
	      cess is not restricted with permit_mx_backup_networks.

       o      Safety: as of Postfix version 2.3,  permit_mx_backup  no	longer
	      accepts the address when the local mail system is	primary	MX for
	      the recipient domain.  Exception:	permit_mx_backup  accepts  the
	      address  when  it	 specifies an authorized destination (see per-
	      mit_auth_destination for definition).

       o      Limitation: mail may be rejected in  case	 of  a	temporary  DNS
	      lookup problem with Postfix prior	to version 2.0.

       reject_non_fqdn_recipient
	      Reject  the  request  when  the RCPT TO address is not in	fully-
	      qualified	domain form, as	required by the	RFC.
	      The non_fqdn_reject_code parameter specifies the	response  code
	      for rejected requests (default: 504).

       reject_rhsbl_recipient rbl_domain=d.d.d.d
	      Reject  the request when the RCPT	TO domain is listed with the A
	      record "d.d.d.d" under rbl_domain	(Postfix version 2.1 and later
	      only).  Each "d" is a number, or a pattern inside	"[]" that con-
	      tains one	or more	";"-separated numbers or number..number	ranges
	      (Postfix	version	2.8 and	later).	If no "=d.d.d.d" is specified,
	      reject the request when the RCPT TO domain is listed with	any  A
	      record under rbl_domain.
	      The  maps_rbl_reject_code	 parameter specifies the response code
	      for rejected requests (default: 554); the	default_rbl_reply  pa-
	      rameter  specifies  the  default	server	reply; and the rbl_re-
	      ply_maps parameter specifies tables with server replies  indexed
	      by rbl_domain.  This feature is available	in Postfix version 2.0
	      and later.

       reject_unauth_destination
	      Reject the request unless	one of the following is	true:

       o      Postfix is mail forwarder: the resolved RCPT TO  domain  matches
	      $relay_domains  or  a subdomain thereof, and contains no sender-
	      specified	routing	(user@elsewhere@domain),

       o      Postfix is the final destination:	the resolved  RCPT  TO	domain
	      matches	$mydestination,	 $inet_interfaces,  $proxy_interfaces,
	      $virtual_alias_domains, or  $virtual_mailbox_domains,  and  con-
	      tains no sender-specified	routing	(user@elsewhere@domain).
	       The  relay_domains_reject_code parameter	specifies the response
	      code for rejected	requests (default: 554).

       reject_unknown_recipient_domain
	      Reject the request when Postfix is not final destination for the
	      recipient	 domain,  and  the  RCPT  TO domain has	no DNS A or MX
	      record, or when it has a malformed MX record such	 as  a	record
	      with a zero-length MX hostname (Postfix version 2.3 and later).
	      The  unknown_address_reject_code parameter specifies the numeri-
	      cal response code	for rejected requests (default:	450).  The re-
	      sponse is	always 450 in case of a	temporary DNS error.
	      The  unknown_address_tempfail_action parameter specifies the ac-
	      tion after a temporary DNS error (default: defer_if_permit).

       reject_unlisted_recipient  (with	 Postfix  version  2.0:	 check_recipi-
       ent_maps)
	      Reject the request when the RCPT TO address is not listed	in the
	      list of valid recipients for its domain class. See the smtpd_re-
	      ject_unlisted_recipient parameter	description for	details.  This
	      feature is available in Postfix 2.1 and later.

       reject_unverified_recipient
	      Reject the request when mail to the RCPT TO address is known  to
	      bounce,  or when the recipient address destination is not	reach-
	      able.  Address verification information is managed by  the  ver-
	      ify(8)  server; see the ADDRESS_VERIFICATION_README file for de-
	      tails.
	      The unverified_recipient_reject_code parameter specifies the nu-
	      merical  response	 code  when an address is known	to bounce (de-
	      fault: 450, change into 550 when you are confident  that	it  is
	      safe to do so).
	      The  unverified_recipient_defer_code parameter specifies the nu-
	      merical response code when an address probe failed due to	a tem-
	      porary problem (default: 450).
	      The unverified_recipient_tempfail_action parameter specifies the
	      action after addres probe	failure	due  to	 a  temporary  problem
	      (default:	defer_if_permit).
	      This feature is available	in Postfix 2.1 and later.

       Other restrictions that are valid in this context:

       o      Generic  restrictions  that can be used in any SMTP command con-
	      text, described under smtpd_client_restrictions.

       o      SMTP   command	specific    restrictions    described	 under
	      smtpd_client_restrictions,      smtpd_helo_restrictions	   and
	      smtpd_sender_restrictions.

       Example:

       smtpd_recipient_restrictions = permit_mynetworks, reject_unauth_destination

smtpd_reject_footer (default: empty)
       Optional	information that is appended after each	SMTP server 4XX	or 5XX
       response.

       Example:

       /etc/postfix/main.cf:
	   smtpd_reject_footer = For assistance, call 800-555-0101.
	    Please provide the following information in	your problem report:
	    time ($localtime), client ($client_address)	and server
	    ($server_name).

       Server response:

	   550-5.5.1 <user@example> Recipient address rejected:	User unknown
	   550 5.5.1 For assistance, call 800-555-0101.	Please provide the
	   following information in your problem report: time (Jan 4 15:42:00),
	   client (192.168.1.248) and server (mail1.example.com).

       Note:  the  above  text	is meant to make it easier to find the Postfix
       logfile records for a failed SMTP  session.  The	 text  itself  is  not
       logged to the Postfix SMTP server's maillog file.

       Be  sure	 to keep the text as short as possible.	Long text may be trun-
       cated before it is logged to the	remote SMTP client's maillog file,  or
       before it is returned to	the sender in a	delivery status	notification.

       This  feature  supports	a  limited  number  of $name attributes	in the
       footer text. These are replaced by their	current	 value	for  the  SMTP
       session:

       client_address
	      The Client IP address that is logged in the maillog file.

       client_port
	      The client TCP port that is logged in the	maillog	file.

       localtime
	      The  server  local  time (Mmm dd hh:mm:ss) that is logged	in the
	      maillog file.

       server_name
	      The server's myhostname value.  This attribute is	made available
	      for  sites  with multiple	MTAs (perhaps behind a load-balancer),
	      where the	server name  can  help	the  server  support  team  to
	      quickly find the right log files.

       Notes:

       o      NOT SUPPORTED are	other attributes such as sender, recipient, or
	      main.cf parameters.

       o      For safety reasons,  text	 that  does  not  match	 $smtpd_expan-
	      sion_filter is censored.

       This  feature supports the two-character	sequence \n as a request for a
       line break in the footer	text. Postfix automatically inserts after each
       line  break the three-digit SMTP	reply code (and	optional enhanced sta-
       tus code) from the original Postfix reject message.

       This feature is available in Postfix 2.8	and later.

smtpd_reject_unlisted_recipient	(default: yes)
       Request that the	Postfix	SMTP server rejects mail for unknown recipient
       addresses,  even	 when no explicit reject_unlisted_recipient access re-
       striction is specified. This prevents the Postfix queue from filling up
       with undeliverable MAILER-DAEMON	messages.

       An  address  is	always considered "known" when it matches a virtual(5)
       alias or	a canonical(5) mapping.

       o      The recipient domain matches $mydestination, $inet_interfaces or
	      $proxy_interfaces, but the recipient is not listed in $local_re-
	      cipient_maps, and	$local_recipient_maps is not null.

       o      The recipient domain matches $virtual_alias_domains but the  re-
	      cipient is not listed in $virtual_alias_maps.

       o      The  recipient  domain  matches $virtual_mailbox_domains but the
	      recipient	is not	listed	in  $virtual_mailbox_maps,  and	 $vir-
	      tual_mailbox_maps	is not null.

       o      The recipient domain matches $relay_domains but the recipient is
	      not listed in $relay_recipient_maps,  and	 $relay_recipient_maps
	      is not null.

       This feature is available in Postfix 2.1	and later.

smtpd_reject_unlisted_sender (default: no)
       Request	that  the Postfix SMTP server rejects mail from	unknown	sender
       addresses, even when no explicit	reject_unlisted_sender access restric-
       tion  is	specified. This	can slow down an explosion of forged mail from
       worms or	viruses.

       An address is always considered "known" when it	matches	 a  virtual(5)
       alias or	a canonical(5) mapping.

       o      The  sender  domain  matches $mydestination, $inet_interfaces or
	      $proxy_interfaces, but the sender	is not listed in $local_recip-
	      ient_maps, and $local_recipient_maps is not null.

       o      The  sender domain matches $virtual_alias_domains	but the	sender
	      is not listed in $virtual_alias_maps.

       o      The  sender  domain  matches  $virtual_mailbox_domains  but  the
	      sender   is  not	listed	in  $virtual_mailbox_maps,  and	 $vir-
	      tual_mailbox_maps	is not null.

       o      The sender domain	matches	$relay_domains but the sender  is  not
	      listed  in  $relay_recipient_maps,  and $relay_recipient_maps is
	      not null.

       This feature is available in Postfix 2.1	and later.

smtpd_restriction_classes (default: empty)
       User-defined aliases for	groups of access restrictions. The aliases can
       be  specified  in  smtpd_recipient_restrictions etc., and on the	right-
       hand side of a Postfix access(5)	table.

       One major application is	for implementing  per-recipient	 UCE  control.
       See the RESTRICTION_CLASS_README	document for other examples.

smtpd_sasl_application_name (default: smtpd)
       The  application	name that the Postfix SMTP server uses for SASL	server
       initialization. This controls the name of the SASL configuration	 file.
       The  default value is smtpd, corresponding to a SASL configuration file
       named smtpd.conf.

       This feature is available in Postfix 2.1	and 2.2. With Postfix  2.3  it
       was renamed to smtpd_sasl_path.

smtpd_sasl_auth_enable (default: no)
       Enable  SASL authentication in the Postfix SMTP server. By default, the
       Postfix SMTP server does	not use	authentication.

       If a remote SMTP	client is authenticated, the permit_sasl_authenticated
       access restriction can be used to permit	relay access, like this:

	   smtpd_recipient_restrictions	=
	       permit_mynetworks, permit_sasl_authenticated, ...

       To  reject  all	SMTP connections from unauthenticated clients, specify
       "smtpd_delay_reject = yes" (which is the	default) and use:

	   smtpd_client_restrictions = permit_sasl_authenticated, reject

       See the SASL_README file	for SASL configuration and operation details.

smtpd_sasl_authenticated_header	(default: no)
       Report the SASL authenticated user name in the smtpd(8)	Received  mes-
       sage header.

       This feature is available in Postfix 2.3	and later.

smtpd_sasl_exceptions_networks (default: empty)
       What  remote  SMTP  clients the Postfix SMTP server will	not offer AUTH
       support to.

       Some clients (Netscape 4	at least) have a bug that causes them  to  re-
       quire  a	login and password whenever AUTH is offered, whether it's nec-
       essary or not. To work around this, specify, for	 example,  $mynetworks
       to prevent Postfix from offering	AUTH to	local clients.

       Specify	a list of network/netmask patterns, separated by commas	and/or
       whitespace. The mask specifies the number of bits in the	 network  part
       of  a host address. You can also	"/file/name" or	"type:table" patterns.
       A "/file/name" pattern is replaced  by  its  contents;  a  "type:table"
       lookup table is matched when a table entry matches a lookup string (the
       lookup result is	ignored).  Continue long lines by  starting  the  next
       line  with whitespace. Specify "!pattern" to exclude an address or net-
       work block from the list.  The form "!/file/name" is supported only  in
       Postfix version 2.4 and later.

       Note:  IP  version 6 address information	must be	specified inside [] in
       the smtpd_sasl_exceptions_networks value, and in	files  specified  with
       "/file/name".   IP  version  6 addresses	contain	the ":"	character, and
       would otherwise be confused with	a "type:table" pattern.

       Example:

       smtpd_sasl_exceptions_networks =	$mynetworks

       This feature is available in Postfix 2.1	and later.

smtpd_sasl_local_domain	(default: empty)
       The name	of the Postfix SMTP server's local SASL	authentication realm.

       By default, the local authentication realm name is the null string.

       Examples:

       smtpd_sasl_local_domain = $mydomain
       smtpd_sasl_local_domain = $myhostname

smtpd_sasl_path	(default: smtpd)
       Implementation-specific information that	the Postfix SMTP server	passes
       through	to  the	 SASL  plug-in	implementation	that  is selected with
       smtpd_sasl_type.	 Typically this	specifies the name of a	 configuration
       file or rendezvous point.

       This feature is available in Postfix 2.3	and later. In earlier releases
       it was called smtpd_sasl_application_name.

smtpd_sasl_security_options (default: noanonymous)
       Postfix SMTP server SASL	security options; as of	Postfix	2.3  the  list
       of available features depends on	the SASL server	implementation that is
       selected	with smtpd_sasl_type.

       The following security features are defined for the cyrus  server  SASL
       implementation:

       Restrict	 what  authentication  mechanisms the Postfix SMTP server will
       offer to	the client.  The list of available  authentication  mechanisms
       is system dependent.

       Specify zero or more of the following:

       noplaintext
	      Disallow methods that use	plaintext passwords.

       noactive
	      Disallow methods subject to active (non-dictionary) attack.

       nodictionary
	      Disallow methods subject to passive (dictionary) attack.

       noanonymous
	      Disallow methods that allow anonymous authentication.

       forward_secrecy
	      Only allow methods that support forward secrecy (Dovecot only).

       mutual_auth
	      Only  allow  methods  that  provide  mutual  authentication (not
	      available	with Cyrus SASL	version	1).

       By default, the Postfix SMTP server accepts plaintext passwords but not
       anonymous logins.

       Warning:	 it appears that clients try authentication methods in the or-
       der as advertised by the	server (e.g., PLAIN ANONYMOUS CRAM-MD5)	 which
       means  that  if	you  disable  plaintext	passwords, clients will	log in
       anonymously, even when they should be able to use CRAM-MD5.  So,	if you
       disable plaintext logins, disable anonymous logins too.	Postfix	treats
       anonymous login as no authentication.

       Example:

       smtpd_sasl_security_options = noanonymous, noplaintext

smtpd_sasl_tls_security_options	(default: $smtpd_sasl_security_options)
       The SASL	authentication security	options	that the Postfix  SMTP	server
       uses for	TLS encrypted SMTP sessions.

       This feature is available in Postfix 2.2	and later.

smtpd_sasl_type	(default: cyrus)
       The  SASL  plug-in type that the	Postfix	SMTP server should use for au-
       thentication. The available types are listed  with  the	"postconf  -a"
       command.

       This feature is available in Postfix 2.3	and later.

smtpd_sender_login_maps	(default: empty)
       Optional	 lookup	 table with the	SASL login names that own sender (MAIL
       FROM) addresses.

       Specify zero or more "type:table" lookup	tables.	With lookups from  in-
       dexed  files  such  as DB or DBM, or from networked tables such as NIS,
       LDAP or SQL, the	following search operations are	done with a sender ad-
       dress of	user@domain:

       1) user@domain
	      This table lookup	is always done and has the highest precedence.

       2) user
	      This  table  lookup  is  done  only  when	the domain part	of the
	      sender address matches $myorigin,	 $mydestination,  $inet_inter-
	      faces or $proxy_interfaces.

       3) @domain
	      This table lookup	is done	last and has the lowest	precedence.

       In all cases the	result of table	lookup must be either "not found" or a
       list of SASL login names	separated by comma and/or whitespace.

smtpd_sender_restrictions (default: empty)
       Optional	restrictions that the Postfix SMTP server applies in the  con-
       text  of	 the MAIL FROM command.	 See SMTPD_ACCESS_README, section "De-
       layed evaluation	of SMTP	access restriction lists" for a	discussion  of
       evaluation context and time.

       The default is to permit	everything.

       Specify	a list of restrictions,	separated by commas and/or whitespace.
       Continue	long lines by starting the next	 line  with  whitespace.   Re-
       strictions are applied in the order as specified; the first restriction
       that matches wins.

       The following restrictions are specific to the sender address  received
       with the	MAIL FROM command.

       check_sender_access type:table
	      Search  the  specified  access(5)	database for the MAIL FROM ad-
	      dress, domain, parent domains, or	localpart@,  and  execute  the
	      corresponding action.

       check_sender_mx_access type:table
	      Search the specified access(5) database for the MX hosts for the
	      MAIL FROM	address, and execute the corresponding action.	 Note:
	      a	result of "OK" is not allowed for safety reasons. Instead, use
	      DUNNO in order to	exclude	specific hosts from blacklists.	  This
	      feature is available in Postfix 2.1 and later.

       check_sender_ns_access type:table
	      Search  the specified access(5) database for the DNS servers for
	      the MAIL FROM address, and  execute  the	corresponding  action.
	      Note:  a	result	of "OK"	is not allowed for safety reasons. In-
	      stead, use DUNNO in order	to exclude specific hosts from	black-
	      lists.  This feature is available	in Postfix 2.1 and later.

       reject_authenticated_sender_login_mismatch
	      Enforces	the  reject_sender_login_mismatch  restriction for au-
	      thenticated clients only.	This feature is	available  in  Postfix
	      version 2.1 and later.

       reject_non_fqdn_sender
	      Reject  the  request when	the MAIL FROM address is not in	fully-
	      qualified	domain form, as	required by the	RFC.
	      The non_fqdn_reject_code parameter specifies the	response  code
	      for rejected requests (default: 504).

       reject_rhsbl_sender rbl_domain=d.d.d.d
	      Reject  the request when the MAIL	FROM domain is listed with the
	      A	record "d.d.d.d" under rbl_domain  (Postfix  version  2.1  and
	      later  only).   Each  "d"	 is a number, or a pattern inside "[]"
	      that contains one	or more	";"-separated numbers or  number..num-
	      ber  ranges (Postfix version 2.8 and later). If no "=d.d.d.d" is
	      specified, reject	the request  when  the	MAIL  FROM  domain  is
	      listed with any A	record under rbl_domain.
	      The  maps_rbl_reject_code	 parameter specifies the response code
	      for rejected requests (default:  554); the default_rbl_reply pa-
	      rameter  specifies  the  default	server	reply; and the rbl_re-
	      ply_maps parameter specifies tables with server replies  indexed
	      by  rbl_domain.	This  feature  is available in Postfix 2.0 and
	      later.

       reject_sender_login_mismatch
	      Reject the request when  $smtpd_sender_login_maps	 specifies  an
	      owner  for  the  MAIL FROM address, but the client is not	(SASL)
	      logged in	as that	MAIL FROM address owner; or when the client is
	      (SASL) logged in,	but the	client login name doesn't own the MAIL
	      FROM address according to	$smtpd_sender_login_maps.

       reject_unauthenticated_sender_login_mismatch
	      Enforces the reject_sender_login_mismatch	restriction for	 unau-
	      thenticated  clients  only. This feature is available in Postfix
	      version 2.1 and later.

       reject_unknown_sender_domain
	      Reject the request when Postfix is not final destination for the
	      sender  address,	and  the  MAIL FROM address has	no DNS A or MX
	      record, or when it has a malformed MX record such	 as  a	record
	      with a zero-length MX hostname (Postfix version 2.3 and later).
	      The  unknown_address_reject_code parameter specifies the numeri-
	      cal response code	for rejected requests (default:	450).  The re-
	      sponse is	always 450 in case of a	temporary DNS error.
	      The  unknown_address_tempfail_action parameter specifies the ac-
	      tion after a temporary DNS error (default: defer_if_permit).

       reject_unlisted_sender
	      Reject the request when the MAIL FROM address is not  listed  in
	      the  list	 of  valid  recipients	for  its domain	class. See the
	      smtpd_reject_unlisted_sender parameter description for  details.
	      This feature is available	in Postfix 2.1 and later.

       reject_unverified_sender
	      Reject  the  request when	mail to	the MAIL FROM address is known
	      to bounce, or when the sender address destination	is not	reach-
	      able.   Address  verification information	is managed by the ver-
	      ify(8) server; see the ADDRESS_VERIFICATION_README file for  de-
	      tails.
	      The unverified_sender_reject_code	parameter specifies the	numer-
	      ical response code when an address is known to bounce  (default:
	      450,  change  into 550 when you are confident that it is safe to
	      do so).
	      The unverified_sender_defer_code	specifies  the	numerical  re-
	      sponse code when an address address probe	failed due to a	tempo-
	      rary problem (default: 450).
	      The unverified_sender_tempfail_action  parameter	specifies  the
	      action  after  address  probe failure due	to a temporary problem
	      (default:	defer_if_permit).
	      This feature is available	in Postfix 2.1 and later.

       Other restrictions that are valid in this context:

       o      Generic restrictions that	can be used in any SMTP	 command  con-
	      text, described under smtpd_client_restrictions.

       o      SMTP    command	 specific    restrictions    described	 under
	      smtpd_client_restrictions	and smtpd_helo_restrictions.

       o      SMTP command specific restrictions described under smtpd_recipi-
	      ent_restrictions.	 When  recipient restrictions are listed under
	      smtpd_sender_restrictions, they have effect only with "smtpd_de-
	      lay_reject  = yes", so that $smtpd_sender_restrictions is	evalu-
	      ated at the time of the RCPT TO command.

       Examples:

       smtpd_sender_restrictions = reject_unknown_sender_domain
       smtpd_sender_restrictions = reject_unknown_sender_domain,
	   check_sender_access hash:/etc/postfix/access

smtpd_service_name (default: smtpd)
       The internal service that postscreen(8)	forwards  allowed  connections
       to. In a	future version there may be different classes of SMTP service.

       This feature is available in Postfix 2.8.

smtpd_soft_error_limit (default: 10)
       The  number  of	errors a remote	SMTP client is allowed to make without
       delivering mail before the Postfix SMTP server slows down all  its  re-
       sponses.

       o      With  Postfix version 2.1	and later, the Postfix SMTP server de-
	      lays all responses by $smtpd_error_sleep_time seconds.

       o      With Postfix versions 2.0	and earlier, the Postfix  SMTP	server
	      delays all responses by (number of errors) seconds.

smtpd_starttls_timeout (default: see postconf -d output)
       The time	limit for Postfix SMTP server write and	read operations	during
       TLS startup and shutdown	 handshake  procedures.	 The  current  default
       value  is stress-dependent. Before Postfix version 2.8, it was fixed at
       300s.

       This feature is available in Postfix 2.2	and later.

smtpd_timeout (default:	normal:	300s, overload:	10s)
       The time	limit for sending a Postfix SMTP server	response and  for  re-
       ceiving	a  remote  SMTP	 client	request. Normally the default limit is
       300s, but it changes under overload to just 10s.	With Postfix  2.5  and
       earlier,	the SMTP server	always uses a time limit of 300s by default.

       Note:  if you set SMTP time limits to very large	values you may have to
       update the global ipc_timeout parameter.

       Time units: s (seconds),	m (minutes), h (hours),	d (days),  w  (weeks).
       The default time	unit is	s (seconds).

smtpd_tls_CAfile (default: empty)
       A  file	containing (PEM	format)	CA certificates	of root	CAs trusted to
       sign either remote SMTP client certificates or intermediate CA certifi-
       cates.	These are loaded into memory before the	smtpd(8) server	enters
       the chroot jail.	If the number of trusted roots is large, consider  us-
       ing  smtpd_tls_CApath  instead, but note	that the latter	directory must
       be present in the chroot	jail if	the smtpd(8) server is chrooted.  This
       file  may  also	be used	to augment the server certificate trust	chain,
       but it is best to include all the required certificates directly	in the
       server certificate file.

       Specify	"tls_append_default_CA = no" to	prevent	Postfix	from appending
       the system-supplied default CAs and trusting third-party	certificates.

       By default (see smtpd_tls_ask_ccert), client certificates are  not  re-
       quested,	 and  smtpd_tls_CAfile should remain empty. If you do make use
       of client certificates, the distinguished names (DNs) of	 the  certifi-
       cate authorities	listed in smtpd_tls_CAfile are sent to the remote SMTP
       client in the client certificate	request	message.  MUAs	with  multiple
       client  certificates may	use the	list of	preferred certificate authori-
       ties to select the correct client certificate.  You  may	 want  to  put
       your  "preferred" CA or CAs in this file, and install other trusted CAs
       in $smtpd_tls_CApath.

       Example:

       smtpd_tls_CAfile	= /etc/postfix/CAcert.pem

       This feature is available in Postfix 2.2	and later.

smtpd_tls_CApath (default: empty)
       A directory containing (PEM format) CA certificates of root CAs trusted
       to  sign	either remote SMTP client certificates or intermediate CA cer-
       tificates. Do not forget	to create the necessary	"hash" links with, for
       example,	  "$OPENSSL_HOME/bin/c_rehash	/etc/postfix/certs".   To  use
       smtpd_tls_CApath	in chroot mode,	this directory (or a copy) must	be in-
       side the	chroot jail.

       Specify	"tls_append_default_CA = no" to	prevent	Postfix	from appending
       the system-supplied default CAs and trusting third-party	certificates.

       By default (see smtpd_tls_ask_ccert), client certificates are  not  re-
       quested,	 and  smtpd_tls_CApath	should	remain	empty.	In contrast to
       smtpd_tls_CAfile,  DNs  of   certificate	  authorities	installed   in
       $smtpd_tls_CApath  are  not  included in	the client certificate request
       message.	MUAs with multiple client certificates may  use	 the  list  of
       preferred certificate authorities to select the correct client certifi-
       cate.   You  may	 want  to  put	your  "preferred"   CA	 or   CAs   in
       $smtpd_tls_CAfile,   and	  install   the	  remaining   trusted  CAs  in
       $smtpd_tls_CApath.

       Example:

       smtpd_tls_CApath	= /etc/postfix/certs

       This feature is available in Postfix 2.2	and later.

smtpd_tls_always_issue_session_ids (default: yes)
       Force the Postfix SMTP server to	issue a	TLS session id,	even when  TLS
       session	caching	 is  turned  off  (smtpd_tls_session_cache_database is
       empty). This behavior is	compatible with	Postfix	< 2.3.

       With Postfix 2.3	and later the Postfix SMTP server can disable  session
       id  generation  when  TLS  session  caching  is	turned off. This keeps
       clients from caching sessions that almost certainly cannot be re-used.

       By default, the Postfix SMTP server always generates TLS	 session  ids.
       This works around a known defect	in mail	client applications such as MS
       Outlook,	and may	also prevent interoperability issues with other	MTAs.

       Example:

       smtpd_tls_always_issue_session_ids = no

       This feature is available in Postfix 2.3	and later.

smtpd_tls_ask_ccert (default: no)
       Ask a remote SMTP client	for a client certificate. This information  is
       needed  for certificate based mail relaying with, for example, the per-
       mit_tls_clientcerts feature.

       Some clients such as Netscape will either complain if no	certificate is
       available (for the list of CAs in $smtpd_tls_CAfile) or will offer mul-
       tiple client certificates to choose from. This may be annoying, so this
       option is "off" by default.

       This feature is available in Postfix 2.2	and later.

smtpd_tls_auth_only (default: no)
       When  TLS encryption is optional	in the Postfix SMTP server, do not an-
       nounce or accept	SASL authentication over unencrypted connections.

       This feature is available in Postfix 2.2	and later.

smtpd_tls_ccert_verifydepth (default: 9)
       The verification	depth for remote SMTP client certificates. A depth  of
       1 is sufficient if the issuing CA is listed in a	local CA file.

       The  default verification depth is 9 (the OpenSSL default) for compati-
       bility with earlier Postfix behavior. Prior to Postfix 2.5, the default
       value  was  5, but the limit was	not actually enforced. If you have set
       this to a lower	non-default  value,  certificates  with	 longer	 trust
       chains  may  now	fail to	verify.	Certificate chains with	1 or 2 CAs are
       common, deeper chains are more rare and any  number  between  5	and  9
       should suffice in practice. You can choose a lower number if, for exam-
       ple, you	trust certificates directly signed by an issuing  CA  but  not
       any CAs it delegates to.

       This feature is available in Postfix 2.2	and later.

smtpd_tls_cert_file (default: empty)
       File  with the Postfix SMTP server RSA certificate in PEM format.  This
       file may	also contain the Postfix SMTP server private RSA key.

       Public Internet MX hosts	without	certificates signed by	a  "reputable"
       CA  must	 generate, and be prepared to present to most clients, a self-
       signed or private-CA signed certificate.	The client will	not be able to
       authenticate  the server, but unless it is running Postfix 2.3 or simi-
       lar software, it	will still insist on a server certificate.

       For servers that	are not	public Internet	MX hosts, Postfix 2.3 supports
       configurations  with  no	certificates. This entails the use of just the
       anonymous TLS ciphers, which are	not supported by typical SMTP clients.
       Since such clients will not, as a rule, fall back to plain text after a
       TLS handshake failure, the server will be unable	to receive email  from
       TLS  enabled  clients.  To avoid	accidental configurations with no cer-
       tificates, Postfix 2.3 enables certificate-less operation only when the
       administrator  explicitly  sets	"smtpd_tls_cert_file = none". This en-
       sures that new Postfix configurations will not accidentally run with no
       certificates.

       Both  RSA  and  DSA  certificates  are  supported.  When	both types are
       present,	the cipher used	determines which certificate will be presented
       to the client.  For Netscape and	OpenSSL	clients	without	special	cipher
       choices the RSA certificate is preferred.

       To enable a remote SMTP client to verify	the Postfix SMTP  server  cer-
       tificate,  the  issuing	CA  certificates must be made available	to the
       client. You should include the required certificates in the server cer-
       tificate	 file,	the  server  certificate first,	then the issuing CA(s)
       (bottom-up order).

       Example:	the certificate	for "server.example.com" was issued by "inter-
       mediate	CA"  which  itself has a certificate of	"root CA".  Create the
       server.pem   file   with	  "cat	 server_cert.pem   intermediate_CA.pem
       root_CA.pem > server.pem".

       If you also want	to verify client certificates issued by	these CAs, you
       can add the CA certificates to the smtpd_tls_CAfile, in which  case  it
       is   not	  necessary   to  have	them  in  the  smtpd_tls_cert_file  or
       smtpd_tls_dcert_file.

       A certificate supplied here must	be usable as an	SSL server certificate
       and hence pass the "openssl verify -purpose sslserver ..." test.

       Example:

       smtpd_tls_cert_file = /etc/postfix/server.pem

       This feature is available in Postfix 2.2	and later.

smtpd_tls_cipherlist (default: empty)
       Obsolete	 Postfix  < 2.3	control	for the	Postfix	SMTP server TLS	cipher
       list. It	is easy	to create inter-operability  problems  by  choosing  a
       non-default cipher list.	Do not use a non-default TLS cipherlist	for MX
       hosts on	the public Internet. Clients that begin	the TLS	handshake, but
       are  unable  to	agree  on a common cipher, may not be able to send any
       email to	the SMTP server. Using a restricted cipher list	 may  be  more
       appropriate  for	 a dedicated MSA or an internal	mailhub, where one can
       exert some control over the TLS software	and settings of	the connecting
       clients.

       Note: do	not use	"" quotes around the parameter value.

       This feature is available with Postfix version 2.2. It is not used with
       Postfix 2.3 and later; use smtpd_tls_mandatory_ciphers instead.

smtpd_tls_ciphers (default: export)
       The minimum TLS cipher grade that the Postfix SMTP server will use with
       opportunistic  TLS  encryption.	Cipher	types  listed in smtpd_tls_ex-
       clude_ciphers are excluded from the base	definition of the selected ci-
       pher  grade. The	default	value "export" ensures maximum inter-operabil-
       ity. Because encryption is optional, stronger controls are  not	appro-
       priate, and this	setting	SHOULD NOT be changed unless the change	is es-
       sential.

       When  TLS  is  mandatory	 the  cipher   grade   is   chosen   via   the
       smtpd_tls_mandatory_ciphers configuration parameter, see	there for syn-
       tax details.

       Example:
       smtpd_tls_ciphers = export

       This feature is available in Postfix 2.6	and later. With	earlier	 Post-
       fix  releases  only the smtpd_tls_mandatory_ciphers parameter is	imple-
       mented, and opportunistic TLS always uses "export" or better (i.e. all)
       ciphers.

smtpd_tls_dcert_file (default: empty)
       File  with the Postfix SMTP server DSA certificate in PEM format.  This
       file may	also contain the Postfix SMTP server private DSA key.

       See the discussion under	smtpd_tls_cert_file for	more details.

       Example:

       smtpd_tls_dcert_file = /etc/postfix/server-dsa.pem

       This feature is available in Postfix 2.2	and later.

smtpd_tls_dh1024_param_file (default: empty)
       File with DH parameters that the	Postfix	SMTP server  should  use  with
       EDH ciphers.

       Instead	of  using  the	exact  same parameter sets as distributed with
       other TLS packages, it is more secure to	generate your own set  of  pa-
       rameters	with something like the	following command:

	   openssl gendh -out /etc/postfix/dh_1024.pem -2 1024

       Your  actual source for entropy may differ. Some	systems	have /dev/ran-
       dom; on other system you	may consider using the "Entropy	Gathering Dae-
       mon EGD", available at http://egd.sourceforge.net/

       Example:

       smtpd_tls_dh1024_param_file = /etc/postfix/dh_1024.pem

       This feature is available with Postfix version 2.2.

smtpd_tls_dh512_param_file (default: empty)
       File  with  DH  parameters that the Postfix SMTP	server should use with
       EDH ciphers.

       See also	the discussion under the smtpd_tls_dh1024_param_file  configu-
       ration parameter.

       Example:

       smtpd_tls_dh512_param_file = /etc/postfix/dh_512.pem

       This feature is available with Postfix version 2.2.

smtpd_tls_dkey_file (default: $smtpd_tls_dcert_file)
       File  with the Postfix SMTP server DSA private key in PEM format.  This
       file may	be combined with the Postfix SMTP server DSA certificate  file
       specified with $smtpd_tls_dcert_file.

       The  private key	must be	accessible without a pass-phrase, i.e. it must
       not be encrypted. File permissions should grant read-only access	to the
       system superuser	account	("root"), and no access	to anyone else.

       This feature is available in Postfix 2.2	and later.

smtpd_tls_eccert_file (default:	empty)
       File  with  the	Postfix	 SMTP  server ECDSA certificate	in PEM format.
       This file may also contain the Postfix SMTP server private ECDSA	key.

       See the discussion under	smtpd_tls_cert_file for	more details.

       Example:

       smtpd_tls_eccert_file = /etc/postfix/ecdsa-scert.pem

       This feature is available in Postfix 2.6	and  later,  when  Postfix  is
       compiled	and linked with	OpenSSL	1.0.0 or later.

smtpd_tls_eckey_file (default: $smtpd_tls_eccert_file)
       File  with  the	Postfix	 SMTP  server ECDSA private key	in PEM format.
       This file may be	combined with the Postfix SMTP server  ECDSA  certifi-
       cate file specified with	$smtpd_tls_eccert_file.

       The  private key	must be	accessible without a pass-phrase, i.e. it must
       not be encrypted. File permissions should grant read-only access	to the
       system superuser	account	("root"), and no access	to anyone else.

       This  feature  is  available  in	Postfix	2.6 and	later, when Postfix is
       compiled	and linked with	OpenSSL	1.0.0 or later.

smtpd_tls_eecdh_grade (default:	see postconf -d	output)
       The Postfix SMTP	server security	 grade	for  ephemeral	elliptic-curve
       Diffie-Hellman (EECDH) key exchange.

       The available choices are:

       none   Don't  use  EECDH.  Ciphers  based on EECDH key exchange will be
	      disabled.	This is	the default in Postfix versions	2.6 and	2.7.

       strong Use EECDH	with approximately 128 bits of security	at  a  reason-
	      able  computational  cost.  This	is  the	 current best-practice
	      trade-off	between	security and computational efficiency. This is
	      the default in Postfix version 2.8 and later.

       ultra  Use  EECDH  with	approximately 192 bits of security at computa-
	      tional cost that is approximately	 twice	as  high  as  128  bit
	      strength	ECC. Barring significant progress in attacks on	ellip-
	      tic curve	crypto-systems,	the "strong" curve is  sufficient  for
	      most users.

       This feature is available in Postfix 2.6	and later, when	it is compiled
       and linked with OpenSSL 1.0.0 or	later.

smtpd_tls_exclude_ciphers (default: empty)
       List of ciphers or cipher types to exclude from the SMTP	server	cipher
       list at all TLS security	levels.	Excluding valid	ciphers	can create in-
       teroperability problems.	DO NOT exclude ciphers unless it is  essential
       to  do so. This is not an OpenSSL cipherlist; it	is a simple list sepa-
       rated by	whitespace and/or commas. The elements are a single cipher, or
       one or more "+" separated cipher	properties, in which case only ciphers
       matching	all the	properties are excluded.

       Examples	(some of these will cause problems):

	   smtpd_tls_exclude_ciphers = aNULL
	   smtpd_tls_exclude_ciphers = MD5, DES
	   smtpd_tls_exclude_ciphers = DES+MD5
	   smtpd_tls_exclude_ciphers = AES256-SHA, DES-CBC3-MD5
	   smtpd_tls_exclude_ciphers = kEDH+aRSA

       The first setting disables anonymous ciphers. The next setting disables
       ciphers	that  use the MD5 digest algorithm or the (single) DES encryp-
       tion algorithm. The next	setting	disables ciphers that use MD5 and  DES
       together.   The	next setting disables the two ciphers "AES256-SHA" and
       "DES-CBC3-MD5". The last	setting	disables ciphers that  use  "EDH"  key
       exchange	with RSA authentication.

       This feature is available in Postfix 2.3	and later.

smtpd_tls_fingerprint_digest (default: md5)
       The  message digest algorithm used to construct client-certificate fin-
       gerprints for check_ccert_access	and  permit_tls_clientcerts.  The  de-
       fault  algorithm	 is  md5, for backwards	compatibility with Postfix re-
       leases prior to 2.5.

       The best	practice algorithm is now sha1.	Recent advances	in hash	 func-
       tion  cryptanalysis  have led to	md5 being deprecated in	favor of sha1.
       However,	as long	as there  are  no  known  "second  pre-image"  attacks
       against md5, its	use in this context can	still be considered safe.

       While  additional  digest algorithms are	often available	with OpenSSL's
       libcrypto, only those used by libssl in SSL cipher suites are available
       to Postfix. For now this	means just md5 or sha1.

       To find the fingerprint of a specific certificate file, with a specific
       digest algorithm, run:

	   $ openssl x509 -noout -fingerprint -digest -in certfile.pem

       The text	to the right of	"=" sign is the	desired	fingerprint.  For  ex-
       ample:

	   $ openssl x509 -noout -fingerprint -sha1 -in	cert.pem
	   SHA1	Fingerprint=D4:6A:AB:19:24:79:F8:32:BB:A6:CB:66:82:C0:8E:9B:EE:29:A8:1A

       Example:	client-certificate access table, with sha1 fingerprints:

	   /etc/postfix/main.cf:
	       smtpd_tls_fingerprint_digest = sha1
	       smtpd_client_restrictions =
		   check_ccert_access hash:/etc/postfix/access,
		   reject
	   /etc/postfix/access:
	       # Action	folded to next line...
	       AF:88:7C:AD:51:95:6F:36:96:F6:01:FB:2E:48:CD:AB:49:25:A2:3B
		   OK
	       85:16:78:FD:73:6E:CE:70:E0:31:5F:0D:3C:C8:6D:C4:2C:24:59:E1
		   permit_auth_destination

       This feature is available in Postfix 2.5	and later.

smtpd_tls_key_file (default: $smtpd_tls_cert_file)
       File  with the Postfix SMTP server RSA private key in PEM format.  This
       file may	be combined with the Postfix SMTP server RSA certificate  file
       specified with $smtpd_tls_cert_file.

       The  private key	must be	accessible without a pass-phrase, i.e. it must
       not be encrypted. File permissions should grant read-only access	to the
       system superuser	account	("root"), and no access	to anyone else.

smtpd_tls_loglevel (default: 0)
       Enable  additional  Postfix  SMTP server	logging	of TLS activity.  Each
       logging level also includes the information that	is logged at  a	 lower
       logging level.

	      0	Disable	logging	of TLS activity.

	      1	Log TLS	handshake and certificate information.

	      2	Log levels during TLS negotiation.

	      3	Log hexadecimal	and ASCII dump of TLS negotiation process.

	      4	 Also  log hexadecimal and ASCII dump of complete transmission
	      after STARTTLS.

       Use "smtpd_tls_loglevel = 3" only in case of problems. Use of  loglevel
       4 is strongly discouraged.

       This feature is available in Postfix 2.2	and later.

smtpd_tls_mandatory_ciphers (default: medium)
       The minimum TLS cipher grade that the Postfix SMTP server will use with
       mandatory TLS encryption. The default grade ("medium") is  sufficiently
       strong  that  any  benefit  from	globally restricting TLS sessions to a
       more stringent grade is likely negligible, especially  given  the  fact
       that  many  implementations  still  do  not  offer any stronger ("high"
       grade) ciphers, while those that	do, will always	use "high"  grade  ci-
       phers.  So  insisting on	"high" grade ciphers is	generally counter-pro-
       ductive.	Allowing "export" or "low" ciphers is  typically  not  a  good
       idea,  as  systems  limited  to	just  these  are  limited  to obsolete
       browsers. No known SMTP clients fail to support at least	 one  "medium"
       or "high" grade cipher.

       The following cipher grades are supported:

       export Enable  "EXPORT" grade or	stronger OpenSSL ciphers.  This	is the
	      most appropriate setting for public MX hosts, and	is always used
	      with  opportunistic TLS encryption. The underlying cipherlist is
	      specified	via the	tls_export_cipherlist configuration parameter,
	      which you	are strongly encouraged	to not change.

       low    Enable  "LOW"  grade or stronger OpenSSL ciphers.	The underlying
	      cipherlist is specified via the tls_low_cipherlist configuration
	      parameter, which you are strongly	encouraged to not change.

       medium Enable  "MEDIUM"	grade  or  stronger OpenSSL ciphers. These use
	      128-bit or longer	symmetric bulk-encryption keys.	 This  is  the
	      default  minimum	strength for mandatory TLS encryption. The un-
	      derlying cipherlist is specified via  the	 tls_medium_cipherlist
	      configuration  parameter,	 which	you are	strongly encouraged to
	      not change.

       high   Enable only "HIGH" grade OpenSSL	ciphers.  The  underlying  ci-
	      pherlist	is specified via the tls_high_cipherlist configuration
	      parameter, which you are strongly	encouraged to not change.

       null   Enable only the "NULL" OpenSSL ciphers, these provide  authenti-
	      cation  without encryption.  This	setting	is only	appropriate in
	      the rare case that all clients are prepared to use NULL  ciphers
	      (not normally enabled in TLS clients). The underlying cipherlist
	      is specified via the tls_null_cipherlist	configuration  parame-
	      ter, which you are strongly encouraged to	not change.

       Cipher	types	listed	 in   smtpd_tls_mandatory_exclude_ciphers   or
       smtpd_tls_exclude_ciphers are excluded from the base definition of  the
       selected	 cipher	 grade.	See smtpd_tls_ciphers for cipher controls that
       apply to	opportunistic TLS.

       The underlying cipherlists for grades other than	"null" include	anony-
       mous ciphers, but these are automatically filtered out if the server is
       configured to ask for client certificates.  You are  very  unlikely  to
       need  to	take any steps to exclude anonymous ciphers, they are excluded
       automatically as	required.  If you must exclude anonymous ciphers  even
       when Postfix does not need or use peer certificates, set	"smtpd_tls_ex-
       clude_ciphers = aNULL". To exclude anonymous ciphers only when  TLS  is
       enforced, set "smtpd_tls_mandatory_exclude_ciphers = aNULL".

       This feature is available in Postfix 2.3	and later.

smtpd_tls_mandatory_exclude_ciphers (default: empty)
       Additional  list	 of  ciphers  or cipher	types to exclude from the SMTP
       server cipher list at mandatory TLS security levels. This list works in
       addition	 to  the exclusions listed with	smtpd_tls_exclude_ciphers (see
       there for syntax	details).

       This feature is available in Postfix 2.3	and later.

smtpd_tls_mandatory_protocols (default:	!SSLv2)
       The SSL/TLS protocols accepted by the Postfix SMTP server  with	manda-
       tory  TLS  encryption.  If  the	list is	empty, the server supports all
       available SSL/TLS protocol versions.  A non-empty value is  a  list  of
       protocol	names separated	by whitespace, commas or colons. The supported
       protocol	names are "SSLv2", "SSLv3" and "TLSv1",	and are	not case  sen-
       sitive.

       Note:  As of OpenSSL 1.0.1 two new protocols are	defined, "TLSv1.1" and
       "TLSv1.2". If an	older Postfix version is linked	against	OpenSSL	 1.0.1
       or  later,  these, or any other new protocol versions, are uncondition-
       ally enabled.

       With Postfix >= 2.5 the parameter syntax	is expanded to support	proto-
       col  exclusions.	 One  can  now	explicitly  exclude  SSLv2  by setting
       "smtpd_tls_mandatory_protocols =	!SSLv2". To  exclude  both  SSLv2  and
       SSLv3 set "smtpd_tls_mandatory_protocols	= !SSLv2, !SSLv3". Listing the
       protocols to include, rather than protocols to exclude,	is  supported,
       but not recommended. The	exclusion form more closely matches the	behav-
       iour when the OpenSSL library is	newer than Postfix.

       Since SSL version 2 has known protocol weaknesses  and  is  now	depre-
       cated,  the  default  setting excludes "SSLv2".	This means that	by de-
       fault, SSL version 2 will not be	used at	the "encrypt" security level.

       Example:

       smtpd_tls_mandatory_protocols = TLSv1
       # Alternative form with Postfix >= 2.5:
       smtpd_tls_mandatory_protocols = !SSLv2, !SSLv3

       This feature is available in Postfix 2.3	and later.

smtpd_tls_protocols (default: empty)
       List of TLS protocols that the Postfix SMTP server will exclude or  in-
       clude  with opportunistic TLS encryption. This parameter	SHOULD be left
       at its default empty value, allowing all	protocols to be	used with  op-
       portunistic TLS.

       In main.cf the values are separated by whitespace, commas or colons. An
       empty value means allow all protocols. The valid	protocol  names,  (see
       \fBfBSSL_get_version(3)),   are	 "SSLv2",   "SSLv3"  and  "TLSv1".  In
       smtp_tls_policy_maps table entries, "protocols"	attribute  values  are
       separated by a colon.

       Note:  As of OpenSSL 1.0.1 two new protocols are	defined, "TLSv1.1" and
       "TLSv1.2". If an	older Postfix version is linked	against	OpenSSL	 1.0.1
       or  later,  these, or any other new protocol versions, are uncondition-
       ally enabled.

       To include a protocol list its name, to exclude	it,  prefix  the  name
       with  a	"!" character. To exclude SSLv2	even for opportunistic TLS set
       "smtpd_tls_protocols = !SSLv2". To exclude both "SSLv2" and "SSLv3" set
       "smtpd_tls_protocols  =	!SSLv2,	!SSLv3". Explicitly listing the	proto-
       cols to include,	rather than protocols to exclude,  is  supported,  but
       not recommended.	 The exclusion form more closely matches the behaviour
       when the	OpenSSL	library	is newer than Postfix.

       Example:
       smtpd_tls_protocols = !SSLv2

       This feature is available in Postfix 2.6	and later.

smtpd_tls_received_header (default: no)
       Request that the	Postfix	SMTP server produces Received:	message	 head-
       ers  that  include  information	about the protocol and cipher used, as
       well as the client CommonName and client	certificate issuer CommonName.
       This  is	 disabled  by  default,	 as the	information may	be modified in
       transit through other mail servers.  Only information that was recorded
       by the final destination	can be trusted.

       This feature is available in Postfix 2.2	and later.

smtpd_tls_req_ccert (default: no)
       With  mandatory	TLS  encryption,  require a trusted remote SMTP	client
       certificate in order to allow TLS connections to	proceed.  This	option
       implies "smtpd_tls_ask_ccert = yes".

       When TLS	encryption is optional,	this setting is	ignored	with a warning
       written to the mail log.

       This feature is available in Postfix 2.2	and later.

smtpd_tls_security_level (default: empty)
       The SMTP	TLS security level for the Postfix SMTP	server;	 when  a  non-
       empty  value  is	 specified,  this  overrides  the  obsolete parameters
       smtpd_use_tls and smtpd_enforce_tls. This  parameter  is	 ignored  with
       "smtpd_tls_wrappermode =	yes".

       Specify one of the following security levels:

       none   TLS will not be used.

       may    Opportunistic  TLS:  announce  STARTTLS support to SMTP clients,
	      but do not require that clients use TLS encryption.

       encrypt
	      Mandatory	TLS encryption:	 announce  STARTTLS  support  to  SMTP
	      clients,	and require that clients use TLS encryption. According
	      to RFC 2487 this MUST NOT	be applied in case of a	 publicly-ref-
	      erenced SMTP server. Instead, this option	should be used only on
	      dedicated	servers.

       Note 1: the "fingerprint", "verify" and "secure"	levels	are  not  sup-
       ported here.  The Postfix SMTP server logs a warning and	uses "encrypt"
       instead.	 To verify SMTP	client certificates, see TLS_README for	a dis-
       cussion	of  the	 smtpd_tls_ask_ccert,  smtpd_tls_req_ccert,  and  per-
       mit_tls_clientcerts features.

       Note 2: The parameter setting "smtpd_tls_security_level = encrypt"  im-
       plies "smtpd_tls_auth_only = yes".

       Note  3:	 when  invoked	via  "sendmail	-bs", Postfix will never offer
       STARTTLS	due to insufficient privileges to access  the  server  private
       key. This is intended behavior.

       This feature is available in Postfix 2.3	and later.

smtpd_tls_session_cache_database (default: empty)
       Name  of	 the file containing the optional Postfix SMTP server TLS ses-
       sion cache. Specify a database type that	supports enumeration, such  as
       btree or	sdbm; there is no need to support concurrent access.  The file
       is created if it	does not exist.	The smtpd(8) daemon does not use  this
       parameter  directly,  rather the	cache is implemented indirectly	in the
       tlsmgr(8) daemon. This means that  per-smtpd-instance  master.cf	 over-
       rides of	this parameter are not effective. Note,	that each of the cache
       databases supported by tlsmgr(8)	daemon:	$smtpd_tls_session_cache_data-
       base,  $smtp_tls_session_cache_database (and with Postfix 2.3 and later
       $lmtp_tls_session_cache_database), needs	to be stored separately. It is
       not  at	this  time possible to store multiple caches in	a single data-
       base.

       Note: dbm databases are not  suitable.  TLS  session  objects  are  too
       large.

       As  of version 2.5, Postfix no longer uses root privileges when opening
       this file. The file  should  now	 be  stored  under  the	 Postfix-owned
       data_directory. As a migration aid, an attempt to open the file under a
       non-Postfix directory is	redirected to  the  Postfix-owned  data_direc-
       tory, and a warning is logged.

       Example:

       smtpd_tls_session_cache_database	= btree:/var/db/postfix/smtpd_scache

       This feature is available in Postfix 2.2	and later.

smtpd_tls_session_cache_timeout	(default: 3600s)
       The  expiration	time of	Postfix	SMTP server TLS	session	cache informa-
       tion. A cache cleanup is	performed periodically	every  $smtpd_tls_ses-
       sion_cache_timeout  seconds. As with $smtpd_tls_session_cache_database,
       this parameter is implemented in	the  tlsmgr(8)	daemon	and  therefore
       per-smtpd-instance master.cf overrides are not possible.

       This feature is available in Postfix 2.2	and later.

smtpd_tls_wrappermode (default:	no)
       Run the Postfix SMTP server in the non-standard "wrapper" mode, instead
       of using	the STARTTLS command.

       If you want to support this service, enable  a  special	port  in  mas-
       ter.cf, and specify "-o smtpd_tls_wrappermode=yes" on the SMTP server's
       command line. Port 465 (smtps) was once chosen for this purpose.

       This feature is available in Postfix 2.2	and later.

smtpd_use_tls (default:	no)
       Opportunistic TLS: announce STARTTLS support to SMTP  clients,  but  do
       not require that	clients	use TLS	encryption.

       Note:  when invoked via "sendmail -bs", Postfix will never offer	START-
       TLS due to insufficient privileges to access the	 server	 private  key.
       This is intended	behavior.

       This  feature  is  available in Postfix 2.2 and later. With Postfix 2.3
       and later use smtpd_tls_security_level instead.

soft_bounce (default: no)
       Safety net to keep mail queued that would otherwise be returned to  the
       sender.	 This  parameter  disables locally-generated bounces, and pre-
       vents the Postfix SMTP  server  from  rejecting	mail  permanently,  by
       changing	5xx reply codes	into 4xx.  However, soft_bounce	is no cure for
       address rewriting mistakes or mail routing mistakes.

       Example:

       soft_bounce = yes

stale_lock_time	(default: 500s)
       The time	after which a stale exclusive  mailbox	lockfile  is  removed.
       This is used for	delivery to file or mailbox.

       Time  units:  s (seconds), m (minutes), h (hours), d (days), w (weeks).
       The default time	unit is	s (seconds).

stress (default: empty)
       This feature is documented in the STRESS_README document.

       This feature is available in Postfix 2.5	and later.

strict_7bit_headers (default: no)
       Reject mail with	8-bit text in message headers. This blocks  mail  from
       poorly written applications.

       This  feature  should  not be enabled on	a general purpose mail server,
       because it is likely to reject legitimate email.

       This feature is available in Postfix 2.0	and later.

strict_8bitmime	(default: no)
       Enable both strict_7bit_headers and strict_8bitmime_body.

       This feature should not be enabled on a general	purpose	 mail  server,
       because it is likely to reject legitimate email.

       This feature is available in Postfix 2.0	and later.

strict_8bitmime_body (default: no)
       Reject  8-bit message body text without 8-bit MIME content encoding in-
       formation.  This	blocks mail from poorly	written	applications.

       Unfortunately, this also	rejects	majordomo approval requests  when  the
       included	request	contains valid 8-bit MIME mail,	and it rejects bounces
       from mailers that do not	MIME encapsulate 8-bit content	(for  example,
       bounces from qmail or from old versions of Postfix).

       This  feature  should  not be enabled on	a general purpose mail server,
       because it is likely to reject legitimate email.

       This feature is available in Postfix 2.0	and later.

strict_mailbox_ownership (default: yes)
       Defer delivery when a mailbox file is not owned by its recipient.   The
       default setting is not backwards	compatible.

       This feature is available in Postfix 2.5.3 and later.

strict_mime_encoding_domain (default: no)
       Reject mail with	invalid	Content-Transfer-Encoding: information for the
       message/* or multipart/*	MIME content types.   This  blocks  mail  from
       poorly written software.

       This  feature  should  not be enabled on	a general purpose mail server,
       because it will reject mail after a single violation.

       This feature is available in Postfix 2.0	and later.

strict_rfc821_envelopes	(default: no)
       Require that addresses received in SMTP MAIL FROM and RCPT TO  commands
       are  enclosed  with <>, and that	those addresses	do not contain RFC 822
       style comments or phrases.  This	stops mail from	poorly	written	 soft-
       ware.

       By default, the Postfix SMTP server accepts RFC 822 syntax in MAIL FROM
       and RCPT	TO addresses.

sun_mailtool_compatibility (default: no)
       Obsolete	SUN mailtool compatibility feature. Instead, use  "mailbox_de-
       livery_lock = dotlock".

swap_bangpath (default:	yes)
       Enable  the  rewriting of "site!user" into "user@site".	This is	neces-
       sary if your machine is connected to UUCP networks.  It is  enabled  by
       default.

       Note:  with  Postfix version 2.2, message header	address	rewriting hap-
       pens only when one of the following conditions is true:

       o      The message is received with the Postfix sendmail(1) command,

       o      The message is received from a network client that matches  $lo-
	      cal_header_rewrite_clients,

       o      The   message   is  received  from  the  network,	 and  the  re-
	      mote_header_rewrite_domain  parameter  specifies	 a   non-empty
	      value.

       To   get	  the  behavior	 before	 Postfix  version  2.2,	 specify  "lo-
       cal_header_rewrite_clients = static:all".

       Example:

       swap_bangpath = no

syslog_facility	(default: mail)
       The syslog facility of Postfix logging. Specify a facility  as  defined
       in syslog.conf(5). The default facility is "mail".

       Warning:	 a non-default syslog_facility setting takes effect only after
       a Postfix process has completed initialization.	Errors during  process
       initialization  will be logged with the default facility.  Examples are
       errors while parsing the	command	line arguments,	and errors  while  ac-
       cessing the Postfix main.cf configuration file.

syslog_name (default: see postconf -d output)
       The  mail  system  name that is prepended to the	process	name in	syslog
       records,	so that	"smtpd"	becomes, for example, "postfix/smtpd".

       Warning:	a non-default syslog_name setting takes	effect	only  after  a
       Postfix	process	 has  completed	 initialization. Errors	during process
       initialization will be logged with the default name. Examples  are  er-
       rors while parsing the command line arguments, and errors while access-
       ing the Postfix main.cf configuration file.

tcp_windowsize (default: 0)
       An optional workaround for  routers  that  break	 TCP  window  scaling.
       Specify	a  value > 0 and < 65536 to enable this	feature.  With Postfix
       TCP servers (smtpd(8), qmqpd(8)), this feature is  implemented  by  the
       Postfix master(8) daemon.

       To  change  this	 parameter without stopping Postfix, you need to first
       terminate all Postfix TCP servers:

	   # postconf -e master_service_disable=inet
	   # postfix reload

       This immediately	terminates all processes that accept  network  connec-
       tions.	Next, you enable Postfix TCP servers with the updated tcp_win-
       dowsize setting:

	   # postconf -e tcp_windowsize=65535 master_service_disable=
	   # postfix reload

       If you skip these  steps	 with  a  running  Postfix  system,  then  the
       tcp_windowsize  change will work	only for Postfix TCP clients (smtp(8),
       lmtp(8)).

       This feature is available in Postfix 2.6	and later.

tls_append_default_CA (default:	no)
       Append the system-supplied default certificate  authority  certificates
       to  the	ones specified with *_tls_CApath or *_tls_CAfile.  The default
       is "no";	this prevents Postfix from trusting  third-party  certificates
       and giving them relay permission	with permit_tls_all_clientcerts.

       This  feature  is available in Postfix 2.4.15, 2.5.11, 2.6.8, 2.7.2 and
       later versions. Specify "tls_append_default_CA  =  yes"	for  backwards
       compatibility,  to  avoid  breaking certificate verification with sites
       that don't use permit_tls_all_clientcerts.

tls_daemon_random_bytes	(default: 32)
       The number of pseudo-random bytes that an smtp(8) or  smtpd(8)  process
       requests	from the tlsmgr(8) server in order to seed its internal	pseudo
       random number generator (PRNG).	The default of 32 bytes	(equivalent to
       256 bits) is sufficient to generate a 128bit (or	168bit)	session	key.

       This feature is available in Postfix 2.2	and later.

tls_disable_workarounds	(default: see postconf -d output)
       List or bit-mask	of OpenSSL bug work-arounds to disable.

       The  OpenSSL  toolkit  includes a set of	work-arounds for buggy SSL/TLS
       implementations.	Applications, such as Postfix, that want  to  maximize
       interoperability	ask the	OpenSSL	library	to enable the full set of rec-
       ommended	work-arounds.

       From time to time, it is	discovered that	a work-around creates a	 secu-
       rity  issue,  and  should  no longer be used. If	upgrading OpenSSL to a
       fixed version is	not an option or an upgrade  is	 not  available	 in  a
       timely  manner,	or  in	closed	environments where no buggy clients or
       servers exist, it may be	appropriate to disable	some  or  all  of  the
       OpenSSL	interoperability  work-arounds.	This parameter specifies which
       bug work-arounds	to disable.

       If the value of the parameter is	a hexadecimal  long  integer  starting
       with  "0x", the bug work-arounds	corresponding to the bits specified in
       its value are removed from the  SSL_OP_ALL  work-around	bit-mask  (see
       openssl/ssl.h  and  SSL_CTX_set_options(3)).  You can specify more bits
       than are	present	in SSL_OP_ALL, excess  bits  are  ignored.  Specifying
       0xFFFFFFFF disables all bug-workarounds on a 32-bit system. This	should
       also be sufficient on 64-bit systems, until  OpenSSL  abandons  support
       for  32-bit  systems and	starts using the high 32 bits of a 64-bit bug-
       workaround mask.

       Otherwise, the parameter	is a white-space or comma  separated  list  of
       specific	 named bug work-arounds	chosen from the	list below. It is pos-
       sible that your OpenSSL version includes	new bug	work-arounds added af-
       ter  your  Postfix  source  code	was last updated, in that case you can
       only disable one	of these via the hexadecimal syntax above.

       MICROSOFT_SESS_ID_BUG
	      See SSL_CTX_set_options(3)

       NETSCAPE_CHALLENGE_BUG
	      See SSL_CTX_set_options(3)

       LEGACY_SERVER_CONNECT
	      See SSL_CTX_set_options(3)

       NETSCAPE_REUSE_CIPHER_CHANGE_BUG
	      also aliased as CVE-2010-4180. Postfix 2.8 disables  this	 work-
	      around  by  default  with	 OpenSSL versions that may predate the
	      fix. Fixed in OpenSSL 0.9.8q and OpenSSL 1.0.0c.

       SSLREF2_REUSE_CERT_TYPE_BUG
	      See SSL_CTX_set_options(3)

       MICROSOFT_BIG_SSLV3_BUFFER
	      See SSL_CTX_set_options(3)

       MSIE_SSLV2_RSA_PADDING
	      also aliased as CVE-2005-2969. Postfix 2.8 disables  this	 work-
	      around  by  default  with	 OpenSSL versions that may predate the
	      fix. Fixed in OpenSSL 0.9.7h and OpenSSL 0.9.8a.

       SSLEAY_080_CLIENT_DH_BUG
	      See SSL_CTX_set_options(3)

       TLS_D5_BUG
	      See SSL_CTX_set_options(3)

       TLS_BLOCK_PADDING_BUG
	      See SSL_CTX_set_options(3)

       TLS_ROLLBACK_BUG
	      See SSL_CTX_set_options(3).  This	is disabled in	OpenSSL	 0.9.7
	      and later. Nobody	should still be	using 0.9.6!

       DONT_INSERT_EMPTY_FRAGMENTS
	      See SSL_CTX_set_options(3)

       CRYPTOPRO_TLSEXT_BUG
	      New with GOST support in OpenSSL 1.0.0.

       This feature is available in Postfix 2.8	and later.

tls_eecdh_strong_curve (default: prime256v1)
       The  elliptic  curve  used  by  the  SMTP  server  for  sensibly	strong
       ephemeral ECDH key exchange. This curve is used	by  the	 Postfix  SMTP
       server  when  "smtpd_tls_eecdh_grade  =	strong".  The phrase "sensibly
       strong" means approximately 128-bit security based on  best  known  at-
       tacks.  The  selected curve must	be implemented by OpenSSL (as reported
       by ecparam(1) with the "-list_curves" option) and be one	of the	curves
       listed  in  Section  5.1.1 of RFC 4492. You should not generally	change
       this setting.

       This default curve is specified in  NSA	"Suite	B"  Cryptography  (see
       http://www.nsa.gov/ia/industry/crypto_suite_b.cfm)    for   information
       classified as SECRET.

       Note: elliptic curve names are poorly standardized; different standards
       groups  are  assigning  different  names	to the same underlying curves.
       The curve with the X9.62	name "prime256v1" is also known	under the SECG
       name "secp256r1", but OpenSSL does not recognize	the latter name.

       This feature is available in Postfix 2.6	and later, when	it is compiled
       and linked with OpenSSL 1.0.0 or	later.

tls_eecdh_ultra_curve (default:	secp384r1)
       The elliptic curve  used	 by  the  SMTP	server	for  maximally	strong
       ephemeral  ECDH	key  exchange.	This curve is used by the Postfix SMTP
       server when "smtpd_tls_eecdh_grade  =  ultra".  The  phrase  "maximally
       strong"	means  approximately  192-bit security based on	best known at-
       tacks.  This additional strength	comes at a  significant	 computational
       cost,  most  users should instead set "smtpd_tls_eecdh_grade = strong".
       The selected curve must be implemented by OpenSSL (as reported  by  ec-
       param(1)	 with  the  "-list_curves"  option)  and  be one of the	curves
       listed in Section 5.1.1 of RFC 4492. You	should	not  generally	change
       this setting.

       This  default  "ultra" curve is specified in NSA	"Suite B" Cryptography
       (see http://www.nsa.gov/ia/industry/crypto_suite_b.cfm) for information
       classified as TOP SECRET.

       This feature is available in Postfix 2.6	and later, when	it is compiled
       and linked with OpenSSL 1.0.0 or	later.

tls_export_cipherlist (default:	ALL:+RC4:@STRENGTH)
       The OpenSSL cipherlist for "EXPORT" or higher grade ciphers.  This  de-
       fines  the  meaning  of the "export" setting in smtpd_tls_mandatory_ci-
       phers, smtp_tls_mandatory_ciphers and lmtp_tls_mandatory_ciphers.  This
       is  the	cipherlist  for	 the opportunistic ("may") TLS client security
       level and is the	default	 cipherlist  for  the  SMTP  server.  You  are
       strongly	 encouraged to not change this setting.	With OpenSSL 1.0.0 and
       later the cipherlist may	start with an "aNULL:" prefix, which  restores
       the  0.9.8-compatible  ordering	of the aNULL ciphers to	the top	of the
       list when they are enabled. This	prefix is  not	needed	with  previous
       OpenSSL releases.

       This feature is available in Postfix 2.3	and later.

tls_high_cipherlist (default: ALL:!EXPORT:!LOW:!MEDIUM:+RC4:@STRENGTH)
       The OpenSSL cipherlist for "HIGH" grade ciphers.	This defines the mean-
       ing   of	  the	"high"	 setting    in	  smtpd_tls_mandatory_ciphers,
       smtp_tls_mandatory_ciphers   and	 lmtp_tls_mandatory_ciphers.  You  are
       strongly	encouraged to not change this setting. With OpenSSL 1.0.0  and
       later  the cipherlist may start with an "aNULL:"	prefix,	which restores
       the 0.9.8-compatible ordering of	the aNULL ciphers to the  top  of  the
       list  when  they	 are  enabled. This prefix is not needed with previous
       OpenSSL releases.

       This feature is available in Postfix 2.3	and later.

tls_low_cipherlist (default: ALL:!EXPORT:+RC4:@STRENGTH)
       The OpenSSL cipherlist for "LOW"	or higher grade	ciphers. This  defines
       the  meaning  of	 the  "low"  setting  in  smtpd_tls_mandatory_ciphers,
       smtp_tls_mandatory_ciphers  and	lmtp_tls_mandatory_ciphers.  You   are
       strongly	encouraged to not change this setting.	With OpenSSL 1.0.0 and
       later the cipherlist may	start with an "aNULL:" prefix, which  restores
       the  0.9.8-compatible  ordering	of the aNULL ciphers to	the top	of the
       list when they are enabled. This	prefix is  not	needed	with  previous
       OpenSSL releases.

       This feature is available in Postfix 2.3	and later.

tls_medium_cipherlist (default:	ALL:!EXPORT:!LOW:+RC4:@STRENGTH)
       The  OpenSSL  cipherlist	for "MEDIUM" or	higher grade ciphers. This de-
       fines the meaning of the	"medium"  setting  in  smtpd_tls_mandatory_ci-
       phers,  smtp_tls_mandatory_ciphers and lmtp_tls_mandatory_ciphers. This
       is the default cipherlist for  mandatory	 TLS  encryption  in  the  TLS
       client  (with anonymous ciphers disabled	when verifying server certifi-
       cates). You are strongly	encouraged to not change this  setting.	  With
       OpenSSL	1.0.0 and later	the cipherlist may start with an "aNULL:" pre-
       fix, which restores the 0.9.8-compatible	ordering of the	aNULL  ciphers
       to the top of the list when they	are enabled. This prefix is not	needed
       with previous OpenSSL releases.

       This feature is available in Postfix 2.3	and later.

tls_null_cipherlist (default: eNULL:!aNULL)
       The OpenSSL cipherlist for "NULL" grade ciphers that provide  authenti-
       cation  without encryption. This	defines	the meaning of the "null" set-
       ting  in	 smtpd_mandatory_tls_ciphers,  smtp_tls_mandatory_ciphers  and
       lmtp_tls_mandatory_ciphers.   You are strongly encouraged to not	change
       this setting.

       This feature is available in Postfix 2.3	and later.

tls_preempt_cipherlist (default: no)
       With SSLv3 and later, use the server's cipher preference	order  instead
       of the client's cipher preference order.

       By  default, the	OpenSSL	server selects the client's most preferred ci-
       pher that the server supports. With SSLv3 and  later,  the  server  may
       choose its own most preferred cipher that is supported (offered)	by the
       client. Setting "tls_preempt_cipherlist = yes"  enables	server	cipher
       preferences.

       While  server  cipher selection may in some cases lead to a more	secure
       or performant cipher choice, there is some risk of interoperability is-
       sues.  In the past, some	SSL clients have listed	lower priority ciphers
       that they did not implement correctly. If the server chooses  a	cipher
       that  the  client prefers less, it may select a cipher whose client im-
       plementation is flawed.

       This feature is available in Postfix 2.8	and later, in combination with
       OpenSSL 0.9.7 and later.

tls_random_bytes (default: 32)
       The  number  of bytes that tlsmgr(8) reads from $tls_random_source when
       (re)seeding the in-memory pseudo	random number generator	 (PRNG)	 pool.
       The  default of 32 bytes	(256 bits) is good enough for 128bit symmetric
       keys.  If using EGD or a	device file, a maximum of 255 bytes is read.

       This feature is available in Postfix 2.2	and later.

tls_random_exchange_name (default: see postconf	-d output)
       Name of the pseudo random number	generator (PRNG) state	file  that  is
       maintained  by  tlsmgr(8).  The file is created when it does not	exist,
       and its length is fixed at 1024 bytes.

       As of version 2.5, Postfix no longer uses root privileges when  opening
       this  file, and the default file	location was changed from ${config_di-
       rectory}/prng_exch to ${data_directory}/prng_exch.  As a	migration aid,
       an attempt to open the file under a non-Postfix directory is redirected
       to the Postfix-owned data_directory, and	a warning is logged.

       This feature is available in Postfix 2.2	and later.

tls_random_prng_update_period (default:	3600s)
       The time	between	attempts by tlsmgr(8) to save the state	of the	pseudo
       random  number  generator  (PRNG)  to the file specified	with $tls_ran-
       dom_exchange_name.

       This feature is available in Postfix 2.2	and later.

tls_random_reseed_period (default: 3600s)
       The maximal time	between	attempts by tlsmgr(8) to re-seed the in-memory
       pseudo  random number generator (PRNG) pool from	external sources.  The
       actual time between re-seeding attempts is calculated using  the	 PRNG,
       and is between 0	and the	time specified.

       This feature is available in Postfix 2.2	and later.

tls_random_source (default: see	postconf -d output)
       The  external  entropy source for the in-memory tlsmgr(8) pseudo	random
       number generator	(PRNG) pool. Be	sure to	specify	a non-blocking source.
       If  this	 source	is not a regular file, the entropy source type must be
       prepended:  egd:/path/to/egd_socket for a source	 with  EGD  compatible
       socket interface, or dev:/path/to/device	for a device file.

       Note:  on  OpenBSD systems specify /dev/arandom when /dev/urandom gives
       timeout errors.

       This feature is available in Postfix 2.2	and later.

tlsproxy_enforce_tls (default: $smtpd_enforce_tls)
       Mandatory TLS: announce STARTTLS	support	to SMTP	clients,  and  require
       that  clients use TLS encryption. See smtpd_enforce_tls for further de-
       tails.

       This feature is available in Postfix 2.8	and later.

tlsproxy_service_name (default:	tlsproxy)
       The name	of the tlsproxy(8) service entry in  master.cf.	 This  service
       performs	plaintext <=> TLS ciphertext conversion.

       This feature is available in Postfix 2.8	and later.

tlsproxy_tls_CAfile (default: $smtpd_tls_CAfile)
       A  file	containing (PEM	format)	CA certificates	of root	CAs trusted to
       sign either remote SMTP client certificates or intermediate CA certifi-
       cates.  See smtpd_tls_CAfile for	further	details.

       This feature is available in Postfix 2.8	and later.

tlsproxy_tls_CApath (default: $smtpd_tls_CApath)
       A directory containing (PEM format) CA certificates of root CAs trusted
       to sign either remote SMTP client certificates or intermediate CA  cer-
       tificates. See smtpd_tls_CApath for further details.

       This feature is available in Postfix 2.8	and later.

tlsproxy_tls_always_issue_session_ids  (default:  $smtpd_tls_always_issue_ses-
       sion_ids)
       Force the Postfix tlsproxy(8) server to issue a TLS  session  id,  even
       when TLS	session	caching	is turned off. See smtpd_tls_always_issue_ses-
       sion_ids	for further details.

       This feature is available in Postfix 2.8	and later.

tlsproxy_tls_ask_ccert (default: $smtpd_tls_ask_ccert)
       Ask  a	remote	 SMTP	client	 for   a   client   certificate.   See
       smtpd_tls_ask_ccert for further details.

       This feature is available in Postfix 2.8	and later.

tlsproxy_tls_ccert_verifydepth (default: $smtpd_tls_ccert_verifydepth)
       The  verification depth for remote SMTP client certificates. A depth of
       1 is sufficient if the issuing CA is listed in a	 local	CA  file.  See
       smtpd_tls_ccert_verifydepth for further details.

       This feature is available in Postfix 2.8	and later.

tlsproxy_tls_cert_file (default: $smtpd_tls_cert_file)
       File with the Postfix tlsproxy(8) server	RSA certificate	in PEM format.
       This file may also contain the Postfix tlsproxy(8) server  private  RSA
       key.  See smtpd_tls_cert_file for further details.

       This feature is available in Postfix 2.8	and later.

tlsproxy_tls_ciphers (default: $smtpd_tls_ciphers)
       The  minimum  TLS cipher	grade that the Postfix tlsproxy(8) server will
       use with	opportunistic TLS encryption. See smtpd_tls_ciphers  for  fur-
       ther details.

       This feature is available in Postfix 2.8	and later.

tlsproxy_tls_dcert_file	(default: $smtpd_tls_dcert_file)
       File with the Postfix tlsproxy(8) server	DSA certificate	in PEM format.
       This file may also contain the Postfix tlsproxy(8) server  private  DSA
       key.  See smtpd_tls_dcert_file for further details.

       This feature is available in Postfix 2.8	and later.

tlsproxy_tls_dh1024_param_file (default: $smtpd_tls_dh1024_param_file)
       File  with DH parameters	that the Postfix tlsproxy(8) server should use
       with EDH	ciphers. See smtpd_tls_dh1024_param_file for further details.

       This feature is available in Postfix 2.8	and later.

tlsproxy_tls_dh512_param_file (default:	$smtpd_tls_dh512_param_file)
       File with DH parameters that the	Postfix	tlsproxy(8) server should  use
       with EDH	ciphers. See smtpd_tls_dh512_param_file	for further details.

       This feature is available in Postfix 2.8	and later.

tlsproxy_tls_dkey_file (default: $smtpd_tls_dkey_file)
       File with the Postfix tlsproxy(8) server	DSA private key	in PEM format.
       This file may be	combined with the Postfix tlsproxy(8) server DSA  cer-
       tificate	   file	   specified	with	$smtpd_tls_dcert_file.	   See
       smtpd_tls_dkey_file for further details.

       This feature is available in Postfix 2.8	and later.

tlsproxy_tls_eccert_file (default: $smtpd_tls_eccert_file)
       File with the Postfix tlsproxy(8) server	ECDSA certificate in PEM  for-
       mat.  This file may also	contain	the Postfix tlsproxy(8)	server private
       ECDSA key.  See smtpd_tls_eccert_file for further details.

       This feature is available in Postfix 2.8	and later.

tlsproxy_tls_eckey_file	(default: $smtpd_tls_eckey_file)
       File with the Postfix tlsproxy(8) server	ECDSA private key in PEM  for-
       mat.   This  file  may  be combined with	the Postfix tlsproxy(8)	server
       ECDSA certificate  file	specified  with	 $smtpd_tls_eccert_file.   See
       smtpd_tls_eckey_file for	further	details.

       This feature is available in Postfix 2.8	and later.

tlsproxy_tls_eecdh_grade (default: $smtpd_tls_eecdh_grade)
       The  Postfix  tlsproxy(8) server	security grade for ephemeral elliptic-
       curve Diffie-Hellman (EECDH) key	 exchange.  See	 smtpd_tls_eecdh_grade
       for further details.

       This feature is available in Postfix 2.8	and later.

tlsproxy_tls_exclude_ciphers (default: $smtpd_tls_exclude_ciphers)
       List  of	ciphers	or cipher types	to exclude from	the tlsproxy(8)	server
       cipher list at all TLS security levels.	See  smtpd_tls_exclude_ciphers
       for further details.

       This feature is available in Postfix 2.8	and later.

tlsproxy_tls_fingerprint_digest	(default: $smtpd_tls_fingerprint_digest)
       The  message digest algorithm used to construct client-certificate fin-
       gerprints. See smtpd_tls_fingerprint_digest for further details.

       This feature is available in Postfix 2.8	and later.

tlsproxy_tls_key_file (default:	$smtpd_tls_key_file)
       File with the Postfix tlsproxy(8) server	RSA private key	in PEM format.
       This  file may be combined with the Postfix tlsproxy(8) server RSA cer-
       tificate	   file	   specified	with	$smtpd_tls_cert_file.	   See
       smtpd_tls_key_file for further details.

       This feature is available in Postfix 2.8	and later.

tlsproxy_tls_loglevel (default:	$smtpd_tls_loglevel)
       Enable  additional  Postfix tlsproxy(8) server logging of TLS activity.
       Each logging level also includes	the information	that is	 logged	 at  a
       lower logging level. See	smtpd_tls_loglevel for further details.

       This feature is available in Postfix 2.8	and later.

tlsproxy_tls_mandatory_ciphers (default: $smtpd_tls_mandatory_ciphers)
       The  minimum  TLS cipher	grade that the Postfix tlsproxy(8) server will
       use with	mandatory TLS encryption. See smtpd_tls_mandatory_ciphers  for
       further details.

       This feature is available in Postfix 2.8	and later.

tlsproxy_tls_mandatory_exclude_ciphers	  (default:   $smtpd_tls_mandatory_ex-
       clude_ciphers)
       Additional list of ciphers or cipher types  to  exclude	from  the  tl-
       sproxy(8)  server  cipher  list	at mandatory TLS security levels.  See
       smtpd_tls_mandatory_exclude_ciphers for further details.

       This feature is available in Postfix 2.8	and later.

tlsproxy_tls_mandatory_protocols (default: $smtpd_tls_mandatory_protocols)
       The SSL/TLS protocols accepted by the Postfix tlsproxy(8)  server  with
       mandatory TLS encryption. If the	list is	empty, the server supports all
       available SSL/TLS protocol versions.  See smtpd_tls_mandatory_protocols
       for further details.

       This feature is available in Postfix 2.8	and later.

tlsproxy_tls_protocols (default: $smtpd_tls_protocols)
       List  of	TLS protocols that the Postfix tlsproxy(8) server will exclude
       or include with opportunistic TLS encryption.  See  smtpd_tls_protocols
       for further details.

       This feature is available in Postfix 2.8	and later.

tlsproxy_tls_req_ccert (default: $smtpd_tls_req_ccert)
       With  mandatory	TLS  encryption,  require a trusted remote SMTP	client
       certificate  in	order  to  allow  TLS  connections  to	proceed.   See
       smtpd_tls_req_ccert for further details.

       This feature is available in Postfix 2.8	and later.

tlsproxy_tls_security_level (default: $smtpd_tls_security_level)
       The  SMTP TLS security level for	the Postfix tlsproxy(8)	server;	when a
       non-empty value is specified, this overrides  the  obsolete  parameters
       smtpd_use_tls  and  smtpd_enforce_tls. See smtpd_tls_security_level for
       further details.

       This feature is available in Postfix 2.8	and later.

tlsproxy_tls_session_cache_timeout (default: $smtpd_tls_session_cache_timeout)

       The expiration time of Postfix tlsproxy(8) server TLS session cache in-
       formation.  A   cache   cleanup	 is   performed	  periodically	 every
       $smtpd_tls_session_cache_timeout	    seconds.	 See	smtpd_tls_ses-
       sion_cache_timeout for further details.

       This feature is available in Postfix 2.8	and later.

tlsproxy_use_tls (default: $smtpd_use_tls)
       Opportunistic TLS: announce STARTTLS support to SMTP  clients,  but  do
       not require that	clients	use TLS	encryption. See	smtpd_use_tls for fur-
       ther details.

       This feature is available in Postfix 2.8	and later.

tlsproxy_watchdog_timeout (default: 10s)
       How much	time a tlsproxy(8) process may take to process local or	remote
       I/O  before  it	is terminated by a built-in watchdog timer.  This is a
       safety mechanism	that prevents tlsproxy(8) from becoming	non-responsive
       due  to	a bug in Postfix itself	or in system software.	To avoid false
       alarms and unnecessary cache corruption this limit cannot be set	 under
       10s.

       Specify	a non-zero time	value (an integral value plus an optional one-
       letter suffix that specifies the	time unit).  Time units: s  (seconds),
       m (minutes), h (hours), d (days), w (weeks).

       This feature is available in Postfix 2.8.

trace_service_name (default: trace)
       The  name  of  the  trace  service.  This service is implemented	by the
       bounce(8) daemon	and maintains a	record of mail deliveries and produces
       a  mail	delivery report	when verbose delivery is requested with	"send-
       mail -v".

       This feature is available in Postfix 2.1	and later.

transport_delivery_slot_cost (default: $default_delivery_slot_cost)
       A transport-specific override for the default_delivery_slot_cost	param-
       eter value, where transport is the master.cf name of the	message	deliv-
       ery transport.

transport_delivery_slot_discount (default: $default_delivery_slot_discount)
       A transport-specific override  for  the	default_delivery_slot_discount
       parameter  value,  where	transport is the master.cf name	of the message
       delivery	transport.

transport_delivery_slot_loan (default: $default_delivery_slot_loan)
       A transport-specific override for the default_delivery_slot_loan	param-
       eter value, where transport is the master.cf name of the	message	deliv-
       ery transport.

transport_destination_concurrency_failed_cohort_limit (default:	 $default_des-
       tination_concurrency_failed_cohort_limit)
       A   transport-specific  override	 for  the  default_destination_concur-
       rency_failed_cohort_limit parameter value, where	transport is the  mas-
       ter.cf name of the message delivery transport.

       This feature is available in Postfix 2.5	and later.

transport_destination_concurrency_limit	(default: $default_destination_concur-
       rency_limit)
       A  transport-specific  override	for  the   default_destination_concur-
       rency_limit  parameter  value, where transport is the master.cf name of
       the message delivery transport.

transport_destination_concurrency_negative_feedback (default:  $default_desti-
       nation_concurrency_negative_feedback)
       A   transport-specific  override	 for  the  default_destination_concur-
       rency_negative_feedback parameter value,	where transport	 is  the  mas-
       ter.cf name of the message delivery transport.

       This feature is available in Postfix 2.5	and later.

transport_destination_concurrency_positive_feedback  (default: $default_desti-
       nation_concurrency_positive_feedback)
       A  transport-specific  override	for  the   default_destination_concur-
       rency_positive_feedback	parameter  value,  where transport is the mas-
       ter.cf name of the message delivery transport.

       This feature is available in Postfix 2.5	and later.

transport_destination_rate_delay (default: $default_destination_rate_delay)
       A transport-specific override  for  the	default_destination_rate_delay
       parameter  value,  where	transport is the master.cf name	of the message
       delivery	transport.

       This feature is available in Postfix 2.5	and later.

transport_destination_recipient_limit  (default:  $default_destination_recipi-
       ent_limit)
       A   transport-specific  override	 for  the  default_destination_recipi-
       ent_limit parameter value, where	transport is the master.cf name	of the
       message delivery	transport.

transport_extra_recipient_limit	(default: $default_extra_recipient_limit)
       A transport-specific override for the default_extra_recipient_limit pa-
       rameter value, where transport is the master.cf name of the message de-
       livery transport.

transport_initial_destination_concurrency  (default: $initial_destination_con-
       currency)
       A transport-specific override for  the  initial_destination_concurrency
       parameter  value,  where	transport is the master.cf name	of the message
       delivery	transport.

       This feature is available in Postfix 2.5	and later.

transport_maps (default: empty)
       Optional	lookup tables with mappings from recipient address to (message
       delivery	 transport,  next-hop  destination).  See transport(5) for de-
       tails.

       Specify zero or more "type:table" lookup	tables.	 If you	use this  fea-
       ture  with local	files, run "postmap /etc/postfix/transport" after mak-
       ing a change.

       For safety reasons, as of Postfix 2.3 this feature does not allow $num-
       ber substitutions in regular expression maps.

       Examples:

       transport_maps =	dbm:/etc/postfix/transport
       transport_maps =	hash:/etc/postfix/transport

transport_minimum_delivery_slots (default: $default_minimum_delivery_slots)
       A  transport-specific  override	for the	default_minimum_delivery_slots
       parameter value,	where transport	is the master.cf name of  the  message
       delivery	transport.

transport_recipient_limit (default: $default_recipient_limit)
       A transport-specific override for the default_recipient_limit parameter
       value, where transport is the master.cf name of	the  message  delivery
       transport.

transport_recipient_refill_delay (default: $default_recipient_refill_delay)
       A  transport-specific  override	for the	default_recipient_refill_delay
       parameter value,	where transport	is the master.cf name of  the  message
       delivery	transport.

       This feature is available in Postfix 2.4	and later.

transport_recipient_refill_limit (default: $default_recipient_refill_limit)
       A  transport-specific  override	for the	default_recipient_refill_limit
       parameter value,	where transport	is the master.cf name of  the  message
       delivery	transport.

       This feature is available in Postfix 2.4	and later.

transport_retry_time (default: 60s)
       The  time  between  attempts  by	the Postfix queue manager to contact a
       malfunctioning message delivery transport.

       Time units: s (seconds),	m (minutes), h (hours),	d (days),  w  (weeks).
       The default time	unit is	s (seconds).

transport_time_limit (default: $command_time_limit)
       A  transport-specific  override	for  the  command_time_limit parameter
       value, where transport is the master.cf name of	the  message  delivery
       transport.

trigger_timeout	(default: 10s)
       The  time limit for sending a trigger to	a Postfix daemon (for example,
       the pickup(8) or	qmgr(8)	daemon). This  time  limit  prevents  programs
       from getting stuck when the mail	system is under	heavy load.

       Time  units:  s (seconds), m (minutes), h (hours), d (days), w (weeks).
       The default time	unit is	s (seconds).

undisclosed_recipients_header (default:	see postconf -d	output)
       Message header that the Postfix cleanup(8) server inserts when  a  mes-
       sage contains no	To: or Cc: message header. With	Postfix	2.8 and	later,
       the default value is empty. With	 Postfix  2.4-2.7,  specify  an	 empty
       value to	disable	this feature.

       Example:

       # Default value before Postfix 2.8.
       # Note: the ":" and ";" are both	required.
       undisclosed_recipients_header = To: undisclosed-recipients:;

unknown_address_reject_code (default: 450)
       The numerical Postfix SMTP server response code when a sender or	recip-
       ient address is rejected	by  the	 reject_unknown_sender_domain  or  re-
       ject_unknown_recipient_domain  restriction.  The	response is always 450
       in case of a temporary DNS error.

       Do not change this unless you have  a  complete	understanding  of  RFC
       2821.

unknown_address_tempfail_action	(default: $reject_tempfail_action)
       The  Postfix  SMTP server's action when reject_unknown_sender_domain or
       reject_unknown_recipient_domain fail due	to a  temporary	 error	condi-
       tion.  Specify  "defer" to defer	the remote SMTP	client request immedi-
       ately. With the default	"defer_if_permit"  action,  the	 Postfix  SMTP
       server  continues  to look for opportunities to reject mail, and	defers
       the client request only if it would otherwise be	accepted.

       This feature is available in Postfix 2.6	and later.

unknown_client_reject_code (default: 450)
       The numerical Postfix SMTP server response code when a  client  without
       valid   address	 <=>  name  mapping  is	 rejected  by  the  reject_un-
       known_client_hostname restriction. The SMTP server always replies  with
       450 when	the mapping failed due to a temporary error condition.

       Do  not	change	this  unless  you have a complete understanding	of RFC
       2821.

unknown_helo_hostname_tempfail_action (default:	$reject_tempfail_action)
       The Postfix  SMTP  server's  action  when  reject_unknown_helo_hostname
       fails due to an temporary error condition. Specify "defer" to defer the
       remote SMTP client request immediately. With the	default	"defer_if_per-
       mit"  action,  the Postfix SMTP server continues	to look	for opportuni-
       ties to reject mail, and	defers the client request  only	 if  it	 would
       otherwise be accepted.

       This feature is available in Postfix 2.6	and later.

unknown_hostname_reject_code (default: 450)
       The numerical Postfix SMTP server response code when the	hostname spec-
       ified with the HELO or EHLO  command  is	 rejected  by  the  reject_un-
       known_helo_hostname restriction.

       Do  not	change	this  unless  you have a complete understanding	of RFC
       2821.

unknown_local_recipient_reject_code (default: 550)
       The numerical Postfix SMTP server response code when  a	recipient  ad-
       dress  is  local,  and $local_recipient_maps specifies a	list of	lookup
       tables that does	not match the recipient.  A recipient address is local
       when  its domain	matches	$mydestination,	$proxy_interfaces or $inet_in-
       terfaces.

       The default setting is 550 (reject mail)	but it is safer	 to  initially
       use  450	 (try  again  later)  so you have time to find out if your lo-
       cal_recipient_maps settings are OK.

       Example:

       unknown_local_recipient_reject_code = 450

       This feature is available in Postfix 2.0	and later.

unknown_relay_recipient_reject_code (default: 550)
       The numerical Postfix SMTP server reply code when a  recipient  address
       matches	$relay_domains,	 and  relay_recipient_maps specifies a list of
       lookup tables that does not match the recipient address.

       This feature is available in Postfix 2.0	and later.

unknown_virtual_alias_reject_code (default: 550)
       The SMTP	server reply code  when	 a  recipient  address	matches	 $vir-
       tual_alias_domains,  and	$virtual_alias_maps specifies a	list of	lookup
       tables that does	not match the recipient	address.

       This feature is available in Postfix 2.0	and later.

unknown_virtual_mailbox_reject_code (default: 550)
       The SMTP	server reply code  when	 a  recipient  address	matches	 $vir-
       tual_mailbox_domains,  and  $virtual_mailbox_maps  specifies  a list of
       lookup tables that does not match the recipient address.

       This feature is available in Postfix 2.0	and later.

unverified_recipient_defer_code	(default: 450)
       The numerical Postfix SMTP server response  when	 a  recipient  address
       probe fails due to a temporary error condition.

       Unlike elsewhere	in Postfix, you	can specify 250	in order to accept the
       address anyway.

       Do not change this unless you have  a  complete	understanding  of  RFC
       2821.

       This feature is available in Postfix 2.6	and later.

unverified_recipient_reject_code (default: 450)
       The  numerical Postfix SMTP server response when	a recipient address is
       rejected	by the reject_unverified_recipient restriction.

       Unlike elsewhere	in Postfix, you	can specify 250	in order to accept the
       address anyway.

       Do  not	change	this  unless  you have a complete understanding	of RFC
       2821.

       This feature is available in Postfix 2.1	and later.

unverified_recipient_reject_reason (default: empty)
       The Postfix SMTP	server's reply when rejecting mail with	reject_unveri-
       fied_recipient.	Do  not	include	the numeric SMTP reply code or the en-
       hanced status code. By default, the response  includes  actual  address
       verification details.

       Example:

       unverified_recipient_reject_reason = Recipient address lookup failed

       This feature is available in Postfix 2.6	and later.

unverified_recipient_tempfail_action (default: $reject_tempfail_action)
       The Postfix SMTP	server's action	when reject_unverified_recipient fails
       due to a	temporary error	condition. Specify "defer" to defer the	remote
       SMTP client request immediately.	With the default "defer_if_permit" ac-
       tion, the Postfix SMTP server continues to look	for  opportunities  to
       reject  mail,  and defers the client request only if it would otherwise
       be accepted.

       This feature is available in Postfix 2.6	and later.

unverified_sender_defer_code (default: 450)
       The numerical Postfix SMTP server response code when a  sender  address
       probe fails due to a temporary error condition.

       Unlike elsewhere	in Postfix, you	can specify 250	in order to accept the
       address anyway.

       Do not change this unless you have  a  complete	understanding  of  RFC
       2821.

       This feature is available in Postfix 2.6	and later.

unverified_sender_reject_code (default:	450)
       The  numerical  Postfix	SMTP server response code when a recipient ad-
       dress is	rejected by the	reject_unverified_sender restriction.

       Unlike elsewhere	in Postfix, you	can specify 250	in order to accept the
       address anyway.

       Do  not	change	this  unless  you have a complete understanding	of RFC
       2821.

       This feature is available in Postfix 2.1	and later.

unverified_sender_reject_reason	(default: empty)
       The Postfix SMTP	server's reply when rejecting mail with	reject_unveri-
       fied_sender. Do not include the numeric SMTP reply code or the enhanced
       status code. By default,	the response includes actual address verifica-
       tion details.

       Example:

       unverified_sender_reject_reason = Sender	address	lookup failed

       This feature is available in Postfix 2.6	and later.

unverified_sender_tempfail_action (default: $reject_tempfail_action)
       The  Postfix  SMTP  server's action when	reject_unverified_sender fails
       due to a	temporary error	condition. Specify "defer" to defer the	remote
       SMTP client request immediately.	With the default "defer_if_permit" ac-
       tion, the Postfix SMTP server continues to look	for  opportunities  to
       reject  mail,  and defers the client request only if it would otherwise
       be accepted.

       This feature is available in Postfix 2.6	and later.

verp_delimiter_filter (default:	-=+)
       The characters Postfix accepts as  VERP	delimiter  characters  on  the
       Postfix sendmail(1) command line	and in SMTP commands.

       This feature is available in Postfix 1.1	and later.

virtual_alias_domains (default:	$virtual_alias_maps)
       Postfix	is  final  destination for the specified list of virtual alias
       domains,	that is, domains for which all addresses are  aliased  to  ad-
       dresses in other	local or remote	domains. The SMTP server validates re-
       cipient addresses with $virtual_alias_maps and rejects non-existent re-
       cipients.   See	also  the  virtual  alias  domain  class  in  the  AD-
       DRESS_CLASS_README file

       This feature is available in Postfix 2.0	and later. The	default	 value
       is backwards compatible with Postfix version 1.1.

       The  default  value is $virtual_alias_maps so that you can keep all in-
       formation about virtual alias domains in	one place.  If you  have  many
       users,  it  is  better  to  separate information	that changes more fre-
       quently (virtual	address	-> local or remote address mapping)  from  in-
       formation  that	changes	 less  frequently  (the	list of	virtual	domain
       names).

       Specify a list of host or domain	names,	"/file/name"  or  "type:table"
       patterns, separated by commas and/or whitespace.	A "/file/name" pattern
       is replaced by its contents; a "type:table"  lookup  table  is  matched
       when  a	table  entry matches a lookup string (the lookup result	is ig-
       nored).	Continue long lines by starting	the next line with whitespace.
       Specify	"!pattern" to exclude a	host or	domain name from the list. The
       form "!/file/name" is supported only in Postfix version 2.4 and later.

       See also	the VIRTUAL_README and ADDRESS_CLASS_README documents for fur-
       ther information.

       Example:

       virtual_alias_domains = virtual1.tld virtual2.tld

virtual_alias_expansion_limit (default:	1000)
       The  maximal  number of addresses that virtual alias expansion produces
       from each original recipient.

       This feature is available in Postfix 2.1	and later.

virtual_alias_maps (default: $virtual_maps)
       Optional	lookup tables that alias specific mail addresses or domains to
       other  local or remote address.	The table format and lookups are docu-
       mented in virtual(5). For an overview of	Postfix	address	 manipulations
       see the ADDRESS_REWRITING_README	document.

       This  feature  is available in Postfix 2.0 and later. The default value
       is backwards compatible with Postfix version 1.1.

       If you use this feature with indexed  files,  run  "postmap  /etc/post-
       fix/virtual" after changing the file.

       Examples:

       virtual_alias_maps = dbm:/etc/postfix/virtual
       virtual_alias_maps = hash:/etc/postfix/virtual

virtual_alias_recursion_limit (default:	1000)
       The  maximal  nesting  depth of virtual alias expansion.	 Currently the
       recursion limit is applied only to the left  branch  of	the  expansion
       graph,  so the depth of the tree	can in the worst case reach the	sum of
       the expansion and recursion limits.  This may change in the future.

       This feature is available in Postfix 2.1	and later.

virtual_destination_concurrency_limit  (default:  $default_destination_concur-
       rency_limit)
       The  maximal  number of parallel	deliveries to the same destination via
       the virtual message delivery transport. This limit is enforced  by  the
       queue  manager.	The message delivery transport name is the first field
       in the entry in the master.cf file.

virtual_destination_recipient_limit   (default:	  $default_destination_recipi-
       ent_limit)
       The  maximal  number  of	recipients per message for the virtual message
       delivery	transport. This	limit is enforced by the  queue	 manager.  The
       message	delivery transport name	is the first field in the entry	in the
       master.cf file.

       Setting this parameter to a value of 1  changes	the  meaning  of  vir-
       tual_destination_concurrency_limit  from	 concurrency  per  domain into
       concurrency per recipient.

virtual_gid_maps (default: empty)
       Lookup tables with the per-recipient group ID  for  virtual(8)  mailbox
       delivery.

       In  a  lookup table, specify a left-hand	side of	"@domain.tld" to match
       any user	in  the	 specified  domain  that  does	not  have  a  specific
       "user@domain.tld" entry.

       When   a	  recipient   address	has   an  optional  address  extension
       (user+foo@domain.tld), the virtual(8) delivery agent looks up the  full
       address	first,	and  when the lookup fails, it looks up	the unextended
       address (user@domain.tld).

       Note 1: for security reasons, the virtual(8) delivery  agent  disallows
       regular expression substitution of $1 etc. in regular expression	lookup
       tables, because that would open a security hole.

       Note 2: for  security  reasons,	the  virtual(8)	 delivery  agent  will
       silently	ignore requests	to use the proxymap(8) server. Instead it will
       open the	table directly.	Before Postfix version 2.2, the	virtual(8) de-
       livery agent will terminate with	a fatal	error.

virtual_mailbox_base (default: empty)
       A  prefix  that	the virtual(8) delivery	agent prepends to all pathname
       results from $virtual_mailbox_maps table	lookups.   This	 is  a	safety
       measure	to  ensure  that an out	of control map doesn't litter the file
       system with mailboxes.  While virtual_mailbox_base could	be set to "/",
       this setting isn't recommended.

       Example:

       virtual_mailbox_base = /var/mail

virtual_mailbox_domains	(default: $virtual_mailbox_maps)
       Postfix is final	destination for	the specified list of domains; mail is
       delivered via the $virtual_transport mail delivery transport.   By  de-
       fault  this  is the Postfix virtual(8) delivery agent.  The SMTP	server
       validates recipient addresses with  $virtual_mailbox_maps  and  rejects
       mail  for non-existent recipients.  See also the	virtual	mailbox	domain
       class in	the ADDRESS_CLASS_README file.

       This parameter expects the same syntax as the mydestination  configura-
       tion parameter.

       This  feature  is available in Postfix 2.0 and later. The default value
       is backwards compatible with Postfix version 1.1.

virtual_mailbox_limit (default:	51200000)
       The maximal size	in  bytes  of  an  individual  virtual(8)  mailbox  or
       maildir file, or	zero (no limit).

virtual_mailbox_lock (default: see postconf -d output)
       How to lock a UNIX-style	virtual(8) mailbox before attempting delivery.
       For a list of available file locking methods,  use  the	"postconf  -l"
       command.

       This  setting  is ignored with maildir style delivery, because such de-
       liveries	are safe without application-level locks.

       Note 1: the dotlock method requires that	the recipient UID or  GID  has
       write access to the parent directory of the recipient's mailbox file.

       Note 2: the default setting of this parameter is	system dependent.

virtual_mailbox_maps (default: empty)
       Optional	 lookup	 tables	 with  all valid addresses in the domains that
       match $virtual_mailbox_domains.

       In a lookup table, specify a left-hand side of "@domain.tld"  to	 match
       any  user  in  the  specified  domain  that  does  not  have a specific
       "user@domain.tld" entry.

       The virtual(8) delivery agent uses this table to	look up	the per-recip-
       ient mailbox or maildir pathname.  If the lookup	result ends in a slash
       ("/"), maildir-style delivery is	carried	out, otherwise the path	is as-
       sumed  to  specify a UNIX-style mailbox file.  Note that	$virtual_mail-
       box_base	is unconditionally prepended to	this path.

       When  a	recipient  address   has   an	optional   address   extension
       (user+foo@domain.tld),  the virtual(8) delivery agent looks up the full
       address first, and when the lookup fails, it looks  up  the  unextended
       address (user@domain.tld).

       Note  1:	 for security reasons, the virtual(8) delivery agent disallows
       regular expression substitution of $1 etc. in regular expression	lookup
       tables, because that would open a security hole.

       Note  2:	 for  security	reasons,  the  virtual(8)  delivery agent will
       silently	ignore requests	to use the proxymap(8) server. Instead it will
       open the	table directly.	Before Postfix version 2.2, the	virtual(8) de-
       livery agent will terminate with	a fatal	error.

virtual_maps (default: empty)
       Optional	lookup tables with a) names of domains for which all addresses
       are  aliased  to	addresses in other local or remote domains, and	b) ad-
       dresses that are	aliased	to addresses in	other local or remote domains.
       Available  before  Postfix  version  2.0.  With Postfix version 2.0 and
       later, this is replaced by separate controls: virtual_alias_domains and
       virtual_alias_maps.

virtual_minimum_uid (default: 100)
       The minimum user	ID value that the virtual(8) delivery agent accepts as
       a result	from $virtual_uid_maps table  lookup.	Returned  values  less
       than this will be rejected, and the message will	be deferred.

virtual_transport (default: virtual)
       The  default mail delivery transport and	next-hop destination for final
       delivery	to domains listed with $virtual_mailbox_domains.  This	infor-
       mation can be overruled with the	transport(5) table.

       Specify	a string of the	form transport:nexthop,	where transport	is the
       name of a mail delivery transport defined in master.cf.	 The  :nexthop
       destination is optional;	its syntax is documented in the	manual page of
       the corresponding delivery agent.

       This feature is available in Postfix 2.0	and later.

virtual_uid_maps (default: empty)
       Lookup tables with the per-recipient user ID that the virtual(8)	deliv-
       ery agent uses while writing to the recipient's mailbox.

       In  a  lookup table, specify a left-hand	side of	"@domain.tld" to match
       any user	in  the	 specified  domain  that  does	not  have  a  specific
       "user@domain.tld" entry.

       When   a	  recipient   address	has   an  optional  address  extension
       (user+foo@domain.tld), the virtual(8) delivery agent looks up the  full
       address	first,	and  when the lookup fails, it looks up	the unextended
       address (user@domain.tld).

       Note 1: for security reasons, the virtual(8) delivery  agent  disallows
       regular expression substitution of $1 etc. in regular expression	lookup
       tables, because that would open a security hole.

       Note 2: for  security  reasons,	the  virtual(8)	 delivery  agent  will
       silently	ignore requests	to use the proxymap(8) server. Instead it will
       open the	table directly.	Before Postfix version 2.2, the	virtual(8) de-
       livery agent will terminate with	a fatal	error.

SEE ALSO
       postconf(1), Postfix configuration parameter maintenance
       master(5), Postfix daemon configuration maintenance

LICENSE
       The Secure Mailer license must be distributed with this software.

AUTHOR(S)
       Wietse Venema
       IBM T.J.	Watson Research
       P.O. Box	704
       Yorktown	Heights, NY 10598, USA

								   POSTCONF(5)

NAME | SYNOPSIS | DESCRIPTION | 2bounce_notice_recipient (default: postmaster) | access_map_defer_code (default: 450) | access_map_reject_code (default: 554) | address_verify_cache_cleanup_interval (default: 12h) | address_verify_default_transport (default: $default_transport) | address_verify_local_transport (default: $local_transport) | address_verify_map (default: see postconf -d output) | address_verify_negative_cache (default: yes) | address_verify_negative_expire_time (default: 3d) | address_verify_negative_refresh_time (default: 3h) | address_verify_poll_count (default: normal: 3, overload: 1) | address_verify_poll_delay (default: 3s) | address_verify_positive_expire_time (default: 31d) | address_verify_positive_refresh_time (default: 7d) | address_verify_relay_transport (default: $relay_transport) | address_verify_relayhost (default: $relayhost) | address_verify_sender (default: $double_bounce_sender) | address_verify_sender_dependent_default_transport_maps (default: $sender_de- | address_verify_sender_dependent_relayhost_maps (default: $sender_dependent_re- | address_verify_service_name (default: verify) | address_verify_transport_maps (default: $transport_maps) | address_verify_virtual_transport (default: $virtual_transport) | alias_database (default: see postconf -d output) | alias_maps (default: see postconf -d output) | allow_mail_to_commands (default: alias, forward) | allow_mail_to_files (default: alias, forward) | allow_min_user (default: no) | allow_percent_hack (default: yes) | allow_untrusted_routing (default: no) | alternate_config_directories (default: empty) | always_add_missing_headers (default: no) | always_bcc (default: empty) | anvil_rate_time_unit (default: 60s) | anvil_status_update_time (default: 600s) | append_at_myorigin (default: yes) | append_dot_mydomain (default: yes) | application_event_drain_time (default: 100s) | authorized_flush_users (default: static:anyone) | authorized_mailq_users (default: static:anyone) | authorized_submit_users (default: static:anyone) | authorized_verp_clients (default: $mynetworks) | backwards_bounce_logfile_compatibility (default: yes) | berkeley_db_create_buffer_size (default: 16777216) | berkeley_db_read_buffer_size (default: 131072) | best_mx_transport (default: empty) | biff (default: yes) | body_checks (default: empty) | body_checks_size_limit (default: 51200) | bounce_notice_recipient (default: postmaster) | bounce_queue_lifetime (default: 5d) | bounce_service_name (default: bounce) | bounce_size_limit (default: 50000) | bounce_template_file (default: empty) | broken_sasl_auth_clients (default: no) | canonical_classes (default: envelope_sender, envelope_recipient, | canonical_maps (default: empty) | cleanup_service_name (default: cleanup) | command_directory (default: see postconf -d output) | command_execution_directory (default: empty) | command_expansion_filter (default: see postconf -d output) | command_time_limit (default: 1000s) | config_directory (default: see postconf -d output) | connection_cache_protocol_timeout (default: 5s) | connection_cache_service_name (default: scache) | connection_cache_status_update_time (default: 600s) | connection_cache_ttl_limit (default: 2s) | content_filter (default: empty) | cyrus_sasl_config_path (default: empty) | daemon_directory (default: see postconf -d output) | daemon_timeout (default: 18000s) | data_directory (default: see postconf -d output) | debug_peer_level (default: 2) | debug_peer_list (default: empty) | debugger_command (default: empty) | default_database_type (default: see postconf -d output) | default_delivery_slot_cost (default: 5) | default_delivery_slot_discount (default: 50) | default_delivery_slot_loan (default: 3) | default_destination_concurrency_failed_cohort_limit (default: 1) | default_destination_concurrency_limit (default: 20) | default_destination_concurrency_negative_feedback (default: 1) | default_destination_concurrency_positive_feedback (default: 1) | default_destination_rate_delay (default: 0s) | default_destination_recipient_limit (default: 50) | default_extra_recipient_limit (default: 1000) | default_filter_nexthop (default: empty) | default_minimum_delivery_slots (default: 3) | default_privs (default: nobody) | default_process_limit (default: 100) | default_rbl_reply (default: see postconf -d output) | default_recipient_limit (default: 20000) | default_recipient_refill_delay (default: 5s) | default_recipient_refill_limit (default: 100) | default_transport (default: smtp) | default_verp_delimiters (default: +=) | defer_code (default: 450) | defer_service_name (default: defer) | defer_transports (default: empty) | delay_logging_resolution_limit (default: 2) | delay_notice_recipient (default: postmaster) | delay_warning_time (default: 0h) | deliver_lock_attempts (default: 20) | deliver_lock_delay (default: 1s) | destination_concurrency_feedback_debug (default: no) | detect_8bit_encoding_header (default: yes) | disable_dns_lookups (default: no) | disable_mime_input_processing (default: no) | disable_mime_output_conversion (default: no) | disable_verp_bounces (default: no) | disable_vrfy_command (default: no) | dnsblog_reply_delay (default: 0s) | dnsblog_service_name (default: dnsblog) | dont_remove (default: 0) | double_bounce_sender (default: double-bounce) | duplicate_filter_limit (default: 1000) | empty_address_default_transport_maps_lookup_key (default: <>) | empty_address_recipient (default: MAILER-DAEMON) | empty_address_relayhost_maps_lookup_key (default: <>) | enable_errors_to (default: no) | enable_original_recipient (default: yes) | error_notice_recipient (default: postmaster) | error_service_name (default: error) | execution_directory_expansion_filter (default: see postconf -d output) | expand_owner_alias (default: no) | export_environment (default: see postconf -d output) | extract_recipient_limit (default: 10240) | fallback_relay (default: empty) | fallback_transport (default: empty) | fallback_transport_maps (default: empty) | fast_flush_domains (default: $relay_domains) | fast_flush_purge_time (default: 7d) | fast_flush_refresh_time (default: 12h) | fault_injection_code (default: 0) | flush_service_name (default: flush) | fork_attempts (default: 5) | fork_delay (default: 1s) | forward_expansion_filter (default: see postconf -d output) | forward_path (default: see postconf -d output) | frozen_delivered_to (default: yes) | hash_queue_depth (default: 1) | hash_queue_names (default: deferred, defer) | header_address_token_limit (default: 10240) | header_checks (default: empty) | header_size_limit (default: 102400) | helpful_warnings (default: yes) | home_mailbox (default: empty) | hopcount_limit (default: 50) | html_directory (default: see postconf -d output) | ignore_mx_lookup_error (default: no) | import_environment (default: see postconf -d output) | in_flow_delay (default: 1s) | inet_interfaces (default: all) | inet_protocols (default: ipv4) | initial_destination_concurrency (default: 5) | internal_mail_filter_classes (default: empty) | invalid_hostname_reject_code (default: 501) | ipc_idle (default: version dependent) | ipc_timeout (default: 3600s) | ipc_ttl (default: 1000s) | line_length_limit (default: 2048) | lmtp_address_preference (default: ipv6) | lmtp_assume_final (default: no) | lmtp_bind_address (default: empty) | lmtp_bind_address6 (default: empty) | lmtp_body_checks (default: empty) | lmtp_cache_connection (default: yes) | lmtp_cname_overrides_servername (default: yes) | lmtp_connect_timeout (default: 0s) | lmtp_connection_cache_destinations (default: empty) | lmtp_connection_cache_on_demand (default: yes) | lmtp_connection_cache_time_limit (default: 2s) | lmtp_connection_reuse_time_limit (default: 300s) | lmtp_data_done_timeout (default: 600s) | lmtp_data_init_timeout (default: 120s) | lmtp_data_xfer_timeout (default: 180s) | lmtp_defer_if_no_mx_address_found (default: no) | lmtp_destination_concurrency_limit (default: $default_destination_concur- | lmtp_destination_recipient_limit (default: $default_destination_recipi- | lmtp_discard_lhlo_keyword_address_maps (default: empty) | lmtp_discard_lhlo_keywords (default: empty) | lmtp_dns_resolver_options (default: empty) | lmtp_enforce_tls (default: no) | lmtp_generic_maps (default: empty) | lmtp_header_checks (default: empty) | lmtp_host_lookup (default: dns) | lmtp_lhlo_name (default: $myhostname) | lmtp_lhlo_timeout (default: 300s) | lmtp_line_length_limit (default: 990) | lmtp_mail_timeout (default: 300s) | lmtp_mime_header_checks (default: empty) | lmtp_mx_address_limit (default: 5) | lmtp_mx_session_limit (default: 2) | lmtp_nested_header_checks (default: empty) | lmtp_pix_workaround_delay_time (default: 10s) | lmtp_pix_workaround_maps (default: empty) | lmtp_pix_workaround_threshold_time (default: 500s) | lmtp_pix_workarounds (default: empty) | lmtp_quit_timeout (default: 300s) | lmtp_quote_rfc821_envelope (default: yes) | lmtp_randomize_addresses (default: yes) | lmtp_rcpt_timeout (default: 300s) | lmtp_reply_filter (default: empty) | lmtp_rset_timeout (default: 20s) | lmtp_sasl_auth_cache_name (default: empty) | lmtp_sasl_auth_cache_time (default: 90d) | lmtp_sasl_auth_enable (default: no) | lmtp_sasl_auth_soft_bounce (default: yes) | lmtp_sasl_mechanism_filter (default: empty) | lmtp_sasl_password_maps (default: empty) | lmtp_sasl_path (default: empty) | lmtp_sasl_security_options (default: noplaintext, noanonymous) | lmtp_sasl_tls_security_options (default: $lmtp_sasl_security_options) | lmtp_sasl_tls_verified_security_options (default: $lmtp_sasl_tls_security_op- | lmtp_sasl_type (default: cyrus) | lmtp_send_xforward_command (default: no) | lmtp_sender_dependent_authentication (default: no) | lmtp_skip_5xx_greeting (default: yes) | lmtp_skip_quit_response (default: no) | lmtp_starttls_timeout (default: 300s) | lmtp_tcp_port (default: 24) | lmtp_tls_CAfile (default: empty) | lmtp_tls_CApath (default: empty) | lmtp_tls_block_early_mail_reply (default: empty) | lmtp_tls_cert_file (default: empty) | lmtp_tls_ciphers (default: export) | lmtp_tls_dcert_file (default: empty) | lmtp_tls_dkey_file (default: $lmtp_tls_dcert_file) | lmtp_tls_eccert_file (default: empty) | lmtp_tls_eckey_file (default: empty) | lmtp_tls_enforce_peername (default: yes) | lmtp_tls_exclude_ciphers (default: empty) | lmtp_tls_fingerprint_cert_match (default: empty) | lmtp_tls_fingerprint_digest (default: md5) | lmtp_tls_key_file (default: $lmtp_tls_cert_file) | lmtp_tls_loglevel (default: 0) | lmtp_tls_mandatory_ciphers (default: empty) | lmtp_tls_mandatory_exclude_ciphers (default: empty) | lmtp_tls_mandatory_protocols (default: !SSLv2) | lmtp_tls_note_starttls_offer (default: no) | lmtp_tls_per_site (default: empty) | lmtp_tls_policy_maps (default: empty) | lmtp_tls_protocols (default: empty) | lmtp_tls_scert_verifydepth (default: 9) | lmtp_tls_secure_cert_match (default: nexthop) | lmtp_tls_security_level (default: empty) | lmtp_tls_session_cache_database (default: empty) | lmtp_tls_session_cache_timeout (default: 3600s) | lmtp_tls_verify_cert_match (default: hostname) | lmtp_use_tls (default: no) | lmtp_xforward_timeout (default: 300s) | local_command_shell (default: empty) | local_destination_concurrency_limit (default: 2) | local_destination_recipient_limit (default: 1) | local_header_rewrite_clients (default: permit_inet_interfaces) | local_recipient_maps (default: proxy:unix:passwd.byname $alias_maps) | local_transport (default: local:$myhostname) | luser_relay (default: empty) | mail_name (default: Postfix) | mail_owner (default: postfix) | mail_release_date (default: see postconf -d output) | mail_spool_directory (default: see postconf -d output) | mail_version (default: see postconf -d output) | mailbox_command (default: empty) | mailbox_command_maps (default: empty) | mailbox_delivery_lock (default: see postconf -d output) | mailbox_size_limit (default: 51200000) | mailbox_transport (default: empty) | mailbox_transport_maps (default: empty) | mailq_path (default: see postconf -d output) | manpage_directory (default: see postconf -d output) | maps_rbl_domains (default: empty) | maps_rbl_reject_code (default: 554) | masquerade_classes (default: envelope_sender, header_sender, header_recipient) | masquerade_domains (default: empty) | masquerade_exceptions (default: empty) | master_service_disable (default: empty) | max_idle (default: 100s) | max_use (default: 100) | maximal_backoff_time (default: 4000s) | maximal_queue_lifetime (default: 5d) | message_reject_characters (default: empty) | message_size_limit (default: 10240000) | message_strip_characters (default: empty) | milter_command_timeout (default: 30s) | milter_connect_macros (default: see postconf -d output) | milter_connect_timeout (default: 30s) | milter_content_timeout (default: 300s) | milter_data_macros (default: see postconf -d output) | milter_default_action (default: tempfail) | milter_end_of_data_macros (default: see postconf -d output) | milter_end_of_header_macros (default: see postconf -d output) | milter_header_checks (default: empty) | milter_helo_macros (default: see postconf -d output) | milter_macro_daemon_name (default: $myhostname) | milter_macro_v (default: $mail_name $mail_version) | milter_mail_macros (default: see postconf -d output) | milter_protocol (default: 6) | milter_rcpt_macros (default: see postconf -d output) | milter_unknown_command_macros (default: see postconf -d output) | mime_boundary_length_limit (default: 2048) | mime_header_checks (default: $header_checks) | mime_nesting_limit (default: 100) | minimal_backoff_time (default: 300s) | multi_instance_directories (default: empty) | multi_instance_enable (default: no) | multi_instance_group (default: empty) | multi_instance_name (default: empty) | multi_instance_wrapper (default: empty) | multi_recipient_bounce_reject_code (default: 550) | mydestination (default: $myhostname, localhost.$mydomain, localhost) | mydomain (default: see postconf -d output) | myhostname (default: see postconf -d output) | mynetworks (default: see postconf -d output) | mynetworks_style (default: subnet) | myorigin (default: $myhostname) | nested_header_checks (default: $header_checks) | newaliases_path (default: see postconf -d output) | non_fqdn_reject_code (default: 504) | non_smtpd_milters (default: empty) | notify_classes (default: resource, software) | owner_request_special (default: yes) | parent_domain_matches_subdomains (default: see postconf -d output) | permit_mx_backup_networks (default: empty) | pickup_service_name (default: pickup) | plaintext_reject_code (default: 450) | postmulti_control_commands (default: reload flush) | postmulti_start_commands (default: start) | postmulti_stop_commands (default: see postconf -d output) | postscreen_access_list (default: permit_mynetworks) | postscreen_bare_newline_action (default: ignore) | postscreen_bare_newline_enable (default: no) | postscreen_bare_newline_ttl (default: 30d) | postscreen_blacklist_action (default: ignore) | postscreen_cache_cleanup_interval (default: 12h) | postscreen_cache_map (default: btree:$data_directory/postscreen_cache) | postscreen_cache_retention_time (default: 7d) | postscreen_client_connection_count_limit (default: $smtpd_client_connec- | postscreen_command_count_limit (default: 20) | postscreen_command_filter (default: $smtpd_command_filter) | postscreen_command_time_limit (default: ${stress?10}${stress:300}s) | postscreen_disable_vrfy_command (default: $disable_vrfy_command) | postscreen_discard_ehlo_keyword_address_maps (default: $smtpd_dis- | postscreen_discard_ehlo_keywords (default: $smtpd_discard_ehlo_keywords) | postscreen_dnsbl_action (default: ignore) | postscreen_dnsbl_reply_map (default: empty) | postscreen_dnsbl_sites (default: empty) | postscreen_dnsbl_threshold (default: 1) | postscreen_dnsbl_ttl (default: 1h) | postscreen_enforce_tls (default: $smtpd_enforce_tls) | postscreen_expansion_filter (default: see postconf -d output) | postscreen_forbidden_commands (default: $smtpd_forbidden_commands) | postscreen_greet_action (default: ignore) | postscreen_greet_banner (default: $smtpd_banner) | postscreen_greet_ttl (default: 1d) | postscreen_greet_wait (default: ${stress?2}${stress:6}s) | postscreen_helo_required (default: $smtpd_helo_required) | postscreen_non_smtp_command_action (default: drop) | postscreen_non_smtp_command_enable (default: no) | postscreen_non_smtp_command_ttl (default: 30d) | postscreen_pipelining_action (default: enforce) | postscreen_pipelining_enable (default: no) | postscreen_pipelining_ttl (default: 30d) | postscreen_post_queue_limit (default: $default_process_limit) | postscreen_pre_queue_limit (default: $default_process_limit) | postscreen_reject_footer (default: $smtpd_reject_footer) | postscreen_tls_security_level (default: $smtpd_tls_security_level) | postscreen_use_tls (default: $smtpd_use_tls) | postscreen_watchdog_timeout (default: 10s) | prepend_delivered_header (default: command, file, forward) | process_id (read-only) | process_id_directory (default: pid) | process_name (read-only) | propagate_unmatched_extensions (default: canonical, virtual) | proxy_interfaces (default: empty) | proxy_read_maps (default: see postconf -d output) | proxy_write_maps (default: see postconf -d output) | proxymap_service_name (default: proxymap) | proxywrite_service_name (default: proxywrite) | qmgr_clog_warn_time (default: 300s) | qmgr_daemon_timeout (default: 1000s) | qmgr_fudge_factor (default: 100) | qmgr_ipc_timeout (default: 60s) | qmgr_message_active_limit (default: 20000) | qmgr_message_recipient_limit (default: 20000) | qmgr_message_recipient_minimum (default: 10) | qmqpd_authorized_clients (default: empty) | qmqpd_client_port_logging (default: no) | qmqpd_error_delay (default: 1s) | qmqpd_timeout (default: 300s) | queue_directory (default: see postconf -d output) | queue_file_attribute_count_limit (default: 100) | queue_minfree (default: 0) | queue_run_delay (default: 300s) | queue_service_name (default: qmgr) | rbl_reply_maps (default: empty) | readme_directory (default: see postconf -d output) | receive_override_options (default: empty) | recipient_bcc_maps (default: empty) | recipient_canonical_classes (default: envelope_recipient, header_recipient) | recipient_canonical_maps (default: empty) | recipient_delimiter (default: empty) | reject_code (default: 554) | reject_tempfail_action (default: defer_if_permit) | relay_clientcerts (default: empty) | relay_destination_concurrency_limit (default: $default_destination_concur- | relay_destination_recipient_limit (default: $default_destination_recipi- | relay_domains (default: $mydestination) | relay_domains_reject_code (default: 554) | relay_recipient_maps (default: empty) | relay_transport (default: relay) | relayhost (default: empty) | relocated_maps (default: empty) | remote_header_rewrite_domain (default: empty) | require_home_directory (default: no) | reset_owner_alias (default: no) | resolve_dequoted_address (default: yes) | resolve_null_domain (default: no) | resolve_numeric_domain (default: no) | rewrite_service_name (default: rewrite) | sample_directory (default: /etc/postfix) | send_cyrus_sasl_authzid (default: no) | sender_based_routing (default: no) | sender_bcc_maps (default: empty) | sender_canonical_classes (default: envelope_sender, header_sender) | sender_canonical_maps (default: empty) | sender_dependent_default_transport_maps (default: empty) | sender_dependent_relayhost_maps (default: empty) | sendmail_path (default: see postconf -d output) | service_throttle_time (default: 60s) | setgid_group (default: postdrop) | show_user_unknown_table_name (default: yes) | showq_service_name (default: showq) | smtp_address_preference (default: ipv6) | smtp_always_send_ehlo (default: yes) | smtp_bind_address (default: empty) | smtp_bind_address6 (default: empty) | smtp_body_checks (default: empty) | smtp_cname_overrides_servername (default: version dependent) | smtp_connect_timeout (default: 30s) | smtp_connection_cache_destinations (default: empty) | smtp_connection_cache_on_demand (default: yes) | smtp_connection_cache_reuse_limit (default: 10) | smtp_connection_cache_time_limit (default: 2s) | smtp_connection_reuse_time_limit (default: 300s) | smtp_data_done_timeout (default: 600s) | smtp_data_init_timeout (default: 120s) | smtp_data_xfer_timeout (default: 180s) | smtp_defer_if_no_mx_address_found (default: no) | smtp_destination_concurrency_limit (default: $default_destination_concur- | smtp_destination_recipient_limit (default: $default_destination_recipi- | smtp_discard_ehlo_keyword_address_maps (default: empty) | smtp_discard_ehlo_keywords (default: empty) | smtp_dns_resolver_options (default: empty) | smtp_enforce_tls (default: no) | smtp_fallback_relay (default: $fallback_relay) | smtp_generic_maps (default: empty) | smtp_header_checks (default: empty) | smtp_helo_name (default: $myhostname) | smtp_helo_timeout (default: 300s) | smtp_host_lookup (default: dns) | smtp_line_length_limit (default: 990) | smtp_mail_timeout (default: 300s) | smtp_mime_header_checks (default: empty) | smtp_mx_address_limit (default: 5) | smtp_mx_session_limit (default: 2) | smtp_nested_header_checks (default: empty) | smtp_never_send_ehlo (default: no) | smtp_pix_workaround_delay_time (default: 10s) | smtp_pix_workaround_maps (default: empty) | smtp_pix_workaround_threshold_time (default: 500s) | smtp_pix_workarounds (default: disable_esmtp, delay_dotcrlf) | smtp_quit_timeout (default: 300s) | smtp_quote_rfc821_envelope (default: yes) | smtp_randomize_addresses (default: yes) | smtp_rcpt_timeout (default: 300s) | smtp_reply_filter (default: empty) | smtp_rset_timeout (default: 20s) | smtp_sasl_auth_cache_name (default: empty) | smtp_sasl_auth_cache_time (default: 90d) | smtp_sasl_auth_enable (default: no) | smtp_sasl_auth_soft_bounce (default: yes) | smtp_sasl_mechanism_filter (default: empty) | smtp_sasl_password_maps (default: empty) | smtp_sasl_path (default: empty) | smtp_sasl_security_options (default: noplaintext, noanonymous) | smtp_sasl_tls_security_options (default: $smtp_sasl_security_options) | smtp_sasl_tls_verified_security_options (default: $smtp_sasl_tls_security_op- | smtp_sasl_type (default: cyrus) | smtp_send_xforward_command (default: no) | smtp_sender_dependent_authentication (default: no) | smtp_skip_4xx_greeting (default: yes) | smtp_skip_5xx_greeting (default: yes) | smtp_skip_quit_response (default: yes) | smtp_starttls_timeout (default: 300s) | smtp_tls_CAfile (default: empty) | smtp_tls_CApath (default: empty) | smtp_tls_block_early_mail_reply (default: no) | smtp_tls_cert_file (default: empty) | smtp_tls_cipherlist (default: empty) | smtp_tls_ciphers (default: export) | smtp_tls_dcert_file (default: empty) | smtp_tls_dkey_file (default: $smtp_tls_dcert_file) | smtp_tls_eccert_file (default: empty) | smtp_tls_eckey_file (default: $smtp_tls_eccert_file) | smtp_tls_enforce_peername (default: yes) | smtp_tls_exclude_ciphers (default: empty) | smtp_tls_fingerprint_cert_match (default: empty) | smtp_tls_fingerprint_digest (default: md5) | smtp_tls_key_file (default: $smtp_tls_cert_file) | smtp_tls_loglevel (default: 0) | smtp_tls_mandatory_ciphers (default: medium) | smtp_tls_mandatory_exclude_ciphers (default: empty) | smtp_tls_mandatory_protocols (default: !SSLv2) | smtp_tls_note_starttls_offer (default: no) | smtp_tls_per_site (default: empty) | smtp_tls_policy_maps (default: empty) | smtp_tls_protocols (default: !SSLv2) | smtp_tls_scert_verifydepth (default: 9) | smtp_tls_secure_cert_match (default: nexthop, dot-nexthop) | smtp_tls_security_level (default: empty) | smtp_tls_session_cache_database (default: empty) | smtp_tls_session_cache_timeout (default: 3600s) | smtp_tls_verify_cert_match (default: hostname) | smtp_use_tls (default: no) | smtp_xforward_timeout (default: 300s) | smtpd_authorized_verp_clients (default: $authorized_verp_clients) | smtpd_authorized_xclient_hosts (default: empty) | smtpd_authorized_xforward_hosts (default: empty) | smtpd_banner (default: $myhostname ESMTP $mail_name) | smtpd_client_connection_count_limit (default: 50) | smtpd_client_connection_rate_limit (default: 0) | smtpd_client_event_limit_exceptions (default: $mynetworks) | smtpd_client_message_rate_limit (default: 0) | smtpd_client_new_tls_session_rate_limit (default: 0) | smtpd_client_port_logging (default: no) | smtpd_client_recipient_rate_limit (default: 0) | smtpd_client_restrictions (default: empty) | smtpd_command_filter (default: empty) | smtpd_data_restrictions (default: empty) | smtpd_delay_open_until_valid_rcpt (default: yes) | smtpd_delay_reject (default: yes) | smtpd_discard_ehlo_keyword_address_maps (default: empty) | smtpd_discard_ehlo_keywords (default: empty) | smtpd_end_of_data_restrictions (default: empty) | smtpd_enforce_tls (default: no) | smtpd_error_sleep_time (default: 1s) | smtpd_etrn_restrictions (default: empty) | smtpd_expansion_filter (default: see postconf -d output) | smtpd_forbidden_commands (default: CONNECT, GET, POST) | smtpd_hard_error_limit (default: normal: 20, overload: 1) | smtpd_helo_required (default: no) | smtpd_helo_restrictions (default: empty) | smtpd_history_flush_threshold (default: 100) | smtpd_junk_command_limit (default: normal: 100, overload: 1) | smtpd_milters (default: empty) | smtpd_noop_commands (default: empty) | smtpd_null_access_lookup_key (default: <>) | smtpd_peername_lookup (default: yes) | smtpd_policy_service_max_idle (default: 300s) | smtpd_policy_service_max_ttl (default: 1000s) | smtpd_policy_service_timeout (default: 100s) | smtpd_proxy_ehlo (default: $myhostname) | smtpd_proxy_filter (default: empty) | smtpd_proxy_options (default: empty) | smtpd_proxy_timeout (default: 100s) | smtpd_recipient_limit (default: 1000) | smtpd_recipient_overshoot_limit (default: 1000) | smtpd_recipient_restrictions (default: permit_mynetworks, reject_unauth_desti- | smtpd_reject_footer (default: empty) | smtpd_reject_unlisted_recipient (default: yes) | smtpd_reject_unlisted_sender (default: no) | smtpd_restriction_classes (default: empty) | smtpd_sasl_application_name (default: smtpd) | smtpd_sasl_auth_enable (default: no) | smtpd_sasl_authenticated_header (default: no) | smtpd_sasl_exceptions_networks (default: empty) | smtpd_sasl_local_domain (default: empty) | smtpd_sasl_path (default: smtpd) | smtpd_sasl_security_options (default: noanonymous) | smtpd_sasl_tls_security_options (default: $smtpd_sasl_security_options) | smtpd_sasl_type (default: cyrus) | smtpd_sender_login_maps (default: empty) | smtpd_sender_restrictions (default: empty) | smtpd_service_name (default: smtpd) | smtpd_soft_error_limit (default: 10) | smtpd_starttls_timeout (default: see postconf -d output) | smtpd_timeout (default: normal: 300s, overload: 10s) | smtpd_tls_CAfile (default: empty) | smtpd_tls_CApath (default: empty) | smtpd_tls_always_issue_session_ids (default: yes) | smtpd_tls_ask_ccert (default: no) | smtpd_tls_auth_only (default: no) | smtpd_tls_ccert_verifydepth (default: 9) | smtpd_tls_cert_file (default: empty) | smtpd_tls_cipherlist (default: empty) | smtpd_tls_ciphers (default: export) | smtpd_tls_dcert_file (default: empty) | smtpd_tls_dh1024_param_file (default: empty) | smtpd_tls_dh512_param_file (default: empty) | smtpd_tls_dkey_file (default: $smtpd_tls_dcert_file) | smtpd_tls_eccert_file (default: empty) | smtpd_tls_eckey_file (default: $smtpd_tls_eccert_file) | smtpd_tls_eecdh_grade (default: see postconf -d output) | smtpd_tls_exclude_ciphers (default: empty) | smtpd_tls_fingerprint_digest (default: md5) | smtpd_tls_key_file (default: $smtpd_tls_cert_file) | smtpd_tls_loglevel (default: 0) | smtpd_tls_mandatory_ciphers (default: medium) | smtpd_tls_mandatory_exclude_ciphers (default: empty) | smtpd_tls_mandatory_protocols (default: !SSLv2) | smtpd_tls_protocols (default: empty) | smtpd_tls_received_header (default: no) | smtpd_tls_req_ccert (default: no) | smtpd_tls_security_level (default: empty) | smtpd_tls_session_cache_database (default: empty) | smtpd_tls_session_cache_timeout (default: 3600s) | smtpd_tls_wrappermode (default: no) | smtpd_use_tls (default: no) | soft_bounce (default: no) | stale_lock_time (default: 500s) | stress (default: empty) | strict_7bit_headers (default: no) | strict_8bitmime (default: no) | strict_8bitmime_body (default: no) | strict_mailbox_ownership (default: yes) | strict_mime_encoding_domain (default: no) | strict_rfc821_envelopes (default: no) | sun_mailtool_compatibility (default: no) | swap_bangpath (default: yes) | syslog_facility (default: mail) | syslog_name (default: see postconf -d output) | tcp_windowsize (default: 0) | tls_append_default_CA (default: no) | tls_daemon_random_bytes (default: 32) | tls_disable_workarounds (default: see postconf -d output) | tls_eecdh_strong_curve (default: prime256v1) | tls_eecdh_ultra_curve (default: secp384r1) | tls_export_cipherlist (default: ALL:+RC4:@STRENGTH) | tls_high_cipherlist (default: ALL:!EXPORT:!LOW:!MEDIUM:+RC4:@STRENGTH) | tls_low_cipherlist (default: ALL:!EXPORT:+RC4:@STRENGTH) | tls_medium_cipherlist (default: ALL:!EXPORT:!LOW:+RC4:@STRENGTH) | tls_null_cipherlist (default: eNULL:!aNULL) | tls_preempt_cipherlist (default: no) | tls_random_bytes (default: 32) | tls_random_exchange_name (default: see postconf -d output) | tls_random_prng_update_period (default: 3600s) | tls_random_reseed_period (default: 3600s) | tls_random_source (default: see postconf -d output) | tlsproxy_enforce_tls (default: $smtpd_enforce_tls) | tlsproxy_service_name (default: tlsproxy) | tlsproxy_tls_CAfile (default: $smtpd_tls_CAfile) | tlsproxy_tls_CApath (default: $smtpd_tls_CApath) | tlsproxy_tls_always_issue_session_ids (default: $smtpd_tls_always_issue_ses- | tlsproxy_tls_ask_ccert (default: $smtpd_tls_ask_ccert) | tlsproxy_tls_ccert_verifydepth (default: $smtpd_tls_ccert_verifydepth) | tlsproxy_tls_cert_file (default: $smtpd_tls_cert_file) | tlsproxy_tls_ciphers (default: $smtpd_tls_ciphers) | tlsproxy_tls_dcert_file (default: $smtpd_tls_dcert_file) | tlsproxy_tls_dh1024_param_file (default: $smtpd_tls_dh1024_param_file) | tlsproxy_tls_dh512_param_file (default: $smtpd_tls_dh512_param_file) | tlsproxy_tls_dkey_file (default: $smtpd_tls_dkey_file) | tlsproxy_tls_eccert_file (default: $smtpd_tls_eccert_file) | tlsproxy_tls_eckey_file (default: $smtpd_tls_eckey_file) | tlsproxy_tls_eecdh_grade (default: $smtpd_tls_eecdh_grade) | tlsproxy_tls_exclude_ciphers (default: $smtpd_tls_exclude_ciphers) | tlsproxy_tls_fingerprint_digest (default: $smtpd_tls_fingerprint_digest) | tlsproxy_tls_key_file (default: $smtpd_tls_key_file) | tlsproxy_tls_loglevel (default: $smtpd_tls_loglevel) | tlsproxy_tls_mandatory_ciphers (default: $smtpd_tls_mandatory_ciphers) | tlsproxy_tls_mandatory_exclude_ciphers (default: $smtpd_tls_mandatory_ex- | tlsproxy_tls_mandatory_protocols (default: $smtpd_tls_mandatory_protocols) | tlsproxy_tls_protocols (default: $smtpd_tls_protocols) | tlsproxy_tls_req_ccert (default: $smtpd_tls_req_ccert) | tlsproxy_tls_security_level (default: $smtpd_tls_security_level) | tlsproxy_tls_session_cache_timeout (default: $smtpd_tls_session_cache_timeout) | tlsproxy_use_tls (default: $smtpd_use_tls) | tlsproxy_watchdog_timeout (default: 10s) | trace_service_name (default: trace) | transport_delivery_slot_cost (default: $default_delivery_slot_cost) | transport_delivery_slot_discount (default: $default_delivery_slot_discount) | transport_delivery_slot_loan (default: $default_delivery_slot_loan) | transport_destination_concurrency_failed_cohort_limit (default: $default_des- | transport_destination_concurrency_limit (default: $default_destination_concur- | transport_destination_concurrency_negative_feedback (default: $default_desti- | transport_destination_concurrency_positive_feedback (default: $default_desti- | transport_destination_rate_delay (default: $default_destination_rate_delay) | transport_destination_recipient_limit (default: $default_destination_recipi- | transport_extra_recipient_limit (default: $default_extra_recipient_limit) | transport_initial_destination_concurrency (default: $initial_destination_con- | transport_maps (default: empty) | transport_minimum_delivery_slots (default: $default_minimum_delivery_slots) | transport_recipient_limit (default: $default_recipient_limit) | transport_recipient_refill_delay (default: $default_recipient_refill_delay) | transport_recipient_refill_limit (default: $default_recipient_refill_limit) | transport_retry_time (default: 60s) | transport_time_limit (default: $command_time_limit) | trigger_timeout (default: 10s) | undisclosed_recipients_header (default: see postconf -d output) | unknown_address_reject_code (default: 450) | unknown_address_tempfail_action (default: $reject_tempfail_action) | unknown_client_reject_code (default: 450) | unknown_helo_hostname_tempfail_action (default: $reject_tempfail_action) | unknown_hostname_reject_code (default: 450) | unknown_local_recipient_reject_code (default: 550) | unknown_relay_recipient_reject_code (default: 550) | unknown_virtual_alias_reject_code (default: 550) | unknown_virtual_mailbox_reject_code (default: 550) | unverified_recipient_defer_code (default: 450) | unverified_recipient_reject_code (default: 450) | unverified_recipient_reject_reason (default: empty) | unverified_recipient_tempfail_action (default: $reject_tempfail_action) | unverified_sender_defer_code (default: 450) | unverified_sender_reject_code (default: 450) | unverified_sender_reject_reason (default: empty) | unverified_sender_tempfail_action (default: $reject_tempfail_action) | verp_delimiter_filter (default: -=+) | virtual_alias_domains (default: $virtual_alias_maps) | virtual_alias_expansion_limit (default: 1000) | virtual_alias_maps (default: $virtual_maps) | virtual_alias_recursion_limit (default: 1000) | virtual_destination_concurrency_limit (default: $default_destination_concur- | virtual_destination_recipient_limit (default: $default_destination_recipi- | virtual_gid_maps (default: empty) | virtual_mailbox_base (default: empty) | virtual_mailbox_domains (default: $virtual_mailbox_maps) | virtual_mailbox_limit (default: 51200000) | virtual_mailbox_lock (default: see postconf -d output) | virtual_mailbox_maps (default: empty) | virtual_maps (default: empty) | virtual_minimum_uid (default: 100) | virtual_transport (default: virtual) | virtual_uid_maps (default: empty) | SEE ALSO | LICENSE | AUTHOR(S)

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