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PIPE(8)			    System Manager's Manual		       PIPE(8)

NAME
       pipe - Postfix delivery to external command

SYNOPSIS
       pipe [generic Postfix daemon options] command_attributes...

DESCRIPTION
       The pipe(8) daemon processes requests from the Postfix queue manager to
       deliver messages	to external commands.  This program expects to be  run
       from the	master(8) process manager.

       Message	attributes such	as sender address, recipient address and next-
       hop host	name can be specified as command-line macros that are expanded
       before the external command is executed.

       The  pipe(8)  daemon  updates  queue files and marks recipients as fin-
       ished, or it informs the	queue manager that delivery  should  be	 tried
       again  at  a  later  time.  Delivery  status  reports  are  sent	to the
       bounce(8), defer(8) or trace(8) daemon as appropriate.

SINGLE-RECIPIENT DELIVERY
       Some destinations cannot	handle more than one  recipient	 per  delivery
       request.	 Examples  are pagers or fax machines.	In addition, multi-re-
       cipient delivery	is undesirable when prepending a Delivered-to:	or  X-
       Original-To: message header.

       To  prevent  Postfix  from sending multiple recipients per delivery re-
       quest, specify

	   transport_destination_recipient_limit = 1

       in the Postfix main.cf file, where transport is the name	in  the	 first
       column  of  the	Postfix	 master.cf  entry  for the pipe-based delivery
       transport.

COMMAND	ATTRIBUTE SYNTAX
       The external command attributes are given in the	master.cf file at  the
       end of a	service	definition.  The syntax	is as follows:

       chroot=pathname (optional)
	      Change  the  process root	directory and working directory	to the
	      named directory. This happens before switching to	the privileges
	      specified	 with the user attribute, and before executing the op-
	      tional directory=pathname	directive.  Delivery  is  deferred  in
	      case of failure.

	      This feature is available	as of Postfix 2.3.

       directory=pathname (optional)
	      Change to	the named directory before executing the external com-
	      mand.  The directory must	be accessible for the  user  specified
	      with the user attribute (see below).  The	default	working	direc-
	      tory is $queue_directory.	 Delivery is deferred in case of fail-
	      ure.

	      This feature is available	as of Postfix 2.2.

       eol=string (optional, default: \n)
	      The output record	delimiter. Typically one would use either \r\n
	      or \n. The usual C-style backslash escape	sequences  are	recog-
	      nized:  \a \b \f \n \r \t	\v \ddd	(up to three octal digits) and
	      \\.

       flags=BDFORXhqu.> (optional)
	      Optional message processing flags.  By  default,	a  message  is
	      copied unchanged.

	      B	     Append  a	blank line at the end of each message. This is
		     required by some mail user	agents that recognize "From  "
		     lines only	when preceded by a blank line.

	      D	     Prepend  a	 "Delivered-To:	recipient" message header with
		     the envelope recipient address. Note: for this  to	 work,
		     the  transport_destination_recipient_limit	must be	1 (see
		     SINGLE-RECIPIENT DELIVERY above for details).

		     The D flag	also enforces loop detection (Postfix 2.5  and
		     later):  if  a  message  already contains a Delivered-To:
		     header with the same recipient address, then the  message
		     is	 returned  as undeliverable. The address comparison is
		     case insensitive.

		     This feature is available as of Postfix 2.0.

	      F	     Prepend a "From sender time_stamp"	envelope header	to the
		     message  content.	This is	expected by, for example, UUCP
		     software.

	      O	     Prepend an	"X-Original-To:	recipient" message header with
		     the recipient address as given to Postfix.	Note: for this
		     to	work, the  transport_destination_recipient_limit  must
		     be	1 (see SINGLE-RECIPIENT	DELIVERY above for details).

		     This feature is available as of Postfix 2.0.

	      R	     Prepend  a	 Return-Path: message header with the envelope
		     sender address.

	      X	     Indicate that the external	command	performs final	deliv-
		     ery.   This flag affects the status reported in "success"
		     DSN (delivery status notification)	messages, and  changes
		     it	from "relayed" into "delivered".

		     This feature is available as of Postfix 2.5.

	      h	     Fold  the command-line $original_recipient	and $recipient
		     address domain part (text to the right of the  right-most
		     @	character) to lower case; fold the entire command-line
		     $domain and $nexthop host or domain information to	 lower
		     case.  This is recommended	for delivery via UUCP.

	      q	     Quote  white  space  and  other special characters	in the
		     command-line $sender, $original_recipient and  $recipient
		     address  localparts (text to the left of the right-most @
		     character), according to an 8-bit transparent version  of
		     RFC  822.	 This  is recommended for delivery via UUCP or
		     BSMTP.

		     The result	is compatible with the address parsing of com-
		     mand-line recipients by the Postfix sendmail(1) mail sub-
		     mission command.

		     The q flag	affects	only entire addresses, not the partial
		     address  information from the $user, $extension or	$mail-
		     box command-line macros.

	      u	     Fold the command-line $original_recipient and  $recipient
		     address  localpart	 (text to the left of the right-most @
		     character)	to lower case.	This is	recommended for	deliv-
		     ery via UUCP.

	      .	     Prepend  "."  to  lines starting with ".".	This is	needed
		     by, for example, BSMTP software.

	      >	     Prepend ">" to lines starting with	"From ". This  is  ex-
		     pected by,	for example, UUCP software.

       null_sender=replacement (default: MAILER-DAEMON)
	      Replace  the  null  sender  address (typically used for delivery
	      status notifications) with the specified text when expanding the
	      $sender  command-line  macro, and	when generating	a From_	or Re-
	      turn-Path: message header.

	      If the null sender replacement text is a non-empty  string  then
	      it is affected by	the q flag for address quoting in command-line
	      arguments.

	      The null sender replacement text may be empty; this form is rec-
	      ommended	for  content filters that feed mail back into Postfix.
	      The empty	sender address is not affected by the q	flag  for  ad-
	      dress quoting in command-line arguments.

	      Caution:	a  null	 sender	 address is easily mis-parsed by naive
	      software.	For example, when the pipe(8) daemon executes  a  com-
	      mand such	as:

		  Wrong: command -f$sender -- $recipient

	      the  command  will mis-parse the -f option value when the	sender
	      address is a null	string.	 For correct parsing, specify  $sender
	      as an argument by	itself:

		  Right: command -f $sender -- $recipient

	      This feature is available	as of Postfix 2.3.

       size=size_limit (optional)
	      Don't  deliver  messages that exceed this	size limit (in bytes);
	      return them to the sender	instead.

       user=username (required)

       user=username:groupname
	      Execute the external command with	the user ID and	 group	ID  of
	      the  specified  username.	  The software refuses to execute com-
	      mands with root privileges, or with the privileges of  the  mail
	      system owner. If groupname is specified, the corresponding group
	      ID is used instead of the	group ID of username.

       argv=command... (required)
	      The command to be	executed. This must be specified as  the  last
	      command attribute.  The command is executed directly, i.e. with-
	      out interpretation of shell meta characters by a	shell  command
	      interpreter.

	      In  the command argument vector, the following macros are	recog-
	      nized and	replaced with corresponding information	from the Post-
	      fix queue	manager	delivery request.

	      In addition to the form ${name}, the forms $name and $(name) are
	      also recognized.	Specify	$$ where a single $ is wanted.

	      ${client_address}
		     This macro	expands	to the remote client network address.

		     This feature is available as of Postfix 2.2.

	      ${client_helo}
		     This macro	expands	to the remote client HELO command  pa-
		     rameter.

		     This feature is available as of Postfix 2.2.

	      ${client_hostname}
		     This macro	expands	to the remote client hostname.

		     This feature is available as of Postfix 2.2.

	      ${client_port}
		     This macro	expands	to the remote client TCP port number.

		     This feature is available as of Postfix 2.5.

	      ${client_protocol}
		     This macro	expands	to the remote client protocol.

		     This feature is available as of Postfix 2.2.

	      ${domain}
		     This macro	expands	to the domain portion of the recipient
		     address.  For example, with  an  address  user+foo@domain
		     the domain	is domain.

		     This information is modified by the h flag	for case fold-
		     ing.

		     This feature is available as of Postfix 2.5.

	      ${extension}
		     This macro	expands	to the extension part of  a  recipient
		     address.	For  example,  with an address user+foo@domain
		     the extension is foo.

		     A command-line argument that  contains  ${extension}  ex-
		     pands  into  as  many command-line	arguments as there are
		     recipients.

		     This information is modified by the u flag	for case fold-
		     ing.

	      ${mailbox}
		     This macro	expands	to the complete	local part of a	recip-
		     ient address.  For	example, with an address  user+foo@do-
		     main the mailbox is user+foo.

		     A	command-line argument that contains ${mailbox} expands
		     to	as many	command-line arguments as  there  are  recipi-
		     ents.

		     This information is modified by the u flag	for case fold-
		     ing.

	      ${nexthop}
		     This macro	expands	to the next-hop	hostname.

		     This information is modified by the h flag	for case fold-
		     ing.

	      ${original_recipient}
		     This  macro expands to the	complete recipient address be-
		     fore any address rewriting	or aliasing.

		     A command-line argument that contains  ${original_recipi-
		     ent}  expands  to as many command-line arguments as there
		     are recipients.

		     This information is modified by the hqu flags for quoting
		     and case folding.

		     This feature is available as of Postfix 2.5.

	      ${queue_id}
		     This macro	expands	to the queue id.

		     This feature is available as of Postfix 2.11.

	      ${recipient}
		     This macro	expands	to the complete	recipient address.

		     A	command-line  argument	that contains ${recipient} ex-
		     pands to as many command-line arguments as	there are  re-
		     cipients.

		     This information is modified by the hqu flags for quoting
		     and case folding.

	      ${sasl_method}
		     This macro	expands	to the name of the SASL	authentication
		     mechanism	in  the	 AUTH  command	when  the Postfix SMTP
		     server received the message.

		     This feature is available as of Postfix 2.2.

	      ${sasl_sender}
		     This macro	expands	to the	SASL  sender  name  (i.e.  the
		     original submitter	as per RFC 4954) in the	MAIL FROM com-
		     mand when the Postfix SMTP	server received	the message.

		     This feature is available as of Postfix 2.2.

	      ${sasl_username}
		     This macro	expands	to the SASL user name in the AUTH com-
		     mand when the Postfix SMTP	server received	the message.

		     This feature is available as of Postfix 2.2.

	      ${sender}
		     This macro	expands	to the envelope	sender address.	By de-
		     fault, the	null sender address expands to	MAILER-DAEMON;
		     this  can	be  changed with the null_sender attribute, as
		     described above.

		     This information is modified by the q flag	for quoting.

	      ${size}
		     This macro	expands	to Postfix's idea of the message size,
		     which  is	an approximation of the	size of	the message as
		     delivered.

	      ${user}
		     This macro	expands	to the username	part  of  a  recipient
		     address.	For  example,  with an address user+foo@domain
		     the username part is user.

		     A command-line argument  that  contains  ${user}  expands
		     into  as many command-line	arguments as there are recipi-
		     ents.

		     This information is modified by the u flag	for case fold-
		     ing.

STANDARDS
       RFC 3463	(Enhanced status codes)

DIAGNOSTICS
       Command	exit  status  codes are	expected to follow the conventions de-
       fined in	<sysexits.h>.  Exit status 0 means normal  successful  comple-
       tion.

       In the case of a	non-zero exit status, a	limited	amount of command out-
       put is reported in an delivery status notification.   When  the	output
       begins  with  a	4.X.X  or  5.X.X enhanced status code, the status code
       takes precedence	over the non-zero exit status (Postfix version 2.3 and
       later).

       Problems	 and transactions are logged to	syslogd(8).  Corrupted message
       files are marked	so that	the queue manager can move them	to the corrupt
       queue for further inspection.

SECURITY
       This  program needs a dual personality 1) to access the private Postfix
       queue and IPC mechanisms, and 2)	to execute external  commands  as  the
       specified user. It is therefore security	sensitive.

CONFIGURATION PARAMETERS
       Changes to main.cf are picked up	automatically as pipe(8) processes run
       for only	a limited amount of time. Use the command "postfix reload"  to
       speed up	a change.

       The  text  below	provides only a	parameter summary. See postconf(5) for
       more details including examples.

RESOURCE AND RATE CONTROLS
       In the text below, transport is the first field in a master.cf entry.

       transport_destination_concurrency_limit	 ($default_destination_concur-
       rency_limit)
	      Limit the	number of parallel deliveries to the same destination,
	      for delivery via the named transport.  The limit is enforced  by
	      the Postfix queue	manager.

       transport_destination_recipient_limit	 ($default_destination_recipi-
       ent_limit)
	      Limit the	number of recipients per message delivery, for	deliv-
	      ery via the named	transport.  The	limit is enforced by the Post-
	      fix queue	manager.

       transport_time_limit ($command_time_limit)
	      Limit the	time for delivery to external  command,	 for  delivery
	      via  the named transport.	 The limit is enforced by the pipe de-
	      livery agent.

	      Postfix 2.4 and later support a suffix that specifies  the  time
	      unit:  s (seconds), m (minutes), h (hours), d (days), w (weeks).
	      The default time unit is seconds.

MISCELLANEOUS CONTROLS
       config_directory	(see 'postconf -d' output)
	      The default location of the Postfix main.cf and  master.cf  con-
	      figuration files.

       daemon_timeout (18000s)
	      How  much	time a Postfix daemon process may take to handle a re-
	      quest before it is terminated by a built-in watchdog timer.

       delay_logging_resolution_limit (2)
	      The maximal number of digits after the decimal point  when  log-
	      ging sub-second delay values.

       export_environment (see 'postconf -d' output)
	      The  list	 of  environment variables that	a Postfix process will
	      export to	non-Postfix processes.

       ipc_timeout (3600s)
	      The time limit for sending or receiving information over an  in-
	      ternal communication channel.

       mail_owner (postfix)
	      The  UNIX	 system	 account  that owns the	Postfix	queue and most
	      Postfix daemon processes.

       max_idle	(100s)
	      The maximum amount of time that an idle Postfix  daemon  process
	      waits for	an incoming connection before terminating voluntarily.

       max_use (100)
	      The maximal number of incoming connections that a	Postfix	daemon
	      process will service before terminating voluntarily.

       process_id (read-only)
	      The process ID of	a Postfix command or daemon process.

       process_name (read-only)
	      The process name of a Postfix command or daemon process.

       queue_directory (see 'postconf -d' output)
	      The location of the Postfix top-level queue directory.

       recipient_delimiter (empty)
	      The set of characters that can separate a	user name from its ex-
	      tension  (example:  user+foo),  or a .forward file name from its
	      extension	(example: .forward+foo).

       syslog_facility (mail)
	      The syslog facility of Postfix logging.

       syslog_name (see	'postconf -d' output)
	      The mail system name that	is prepended to	the  process  name  in
	      syslog  records,	so  that  "smtpd" becomes, for example,	"post-
	      fix/smtpd".

SEE ALSO
       qmgr(8),	queue manager
       bounce(8), delivery status reports
       postconf(5), configuration parameters
       master(5), generic daemon options
       master(8), process manager
       syslogd(8), system logging

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

								       PIPE(8)

NAME | SYNOPSIS | DESCRIPTION | SINGLE-RECIPIENT DELIVERY | COMMAND ATTRIBUTE SYNTAX | STANDARDS | DIAGNOSTICS | SECURITY | CONFIGURATION PARAMETERS | RESOURCE AND RATE CONTROLS | MISCELLANEOUS CONTROLS | SEE ALSO | LICENSE | AUTHOR(S)

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