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

NAME
       flush - Postfix fast flush server

SYNOPSIS
       flush [generic Postfix daemon options]

DESCRIPTION
       The flush(8) server maintains a record of deferred mail by destination.
       This information	is used	to improve the performance of  the  SMTP  ETRN
       request,	  and  of  its	command-line  equivalent,  "sendmail  -qR"  or
       "postqueue -f".	This program expects to	 be  run  from	the  master(8)
       process manager.

       The record is implemented as a per-destination logfile with as contents
       the queue IDs of	deferred mail. A logfile is append-only, and is	 trun-
       cated  when  delivery is	requested for the corresponding	destination. A
       destination is the part on the right-hand side of the right-most	 @  in
       an email	address.

       Per-destination	logfiles of deferred mail are maintained only for eli-
       gible destinations. The list of eligible	destinations is	specified with
       the  fast_flush_domains configuration parameter,	which defaults to $re-
       lay_domains.

       This server implements the following requests:

       add sitename queueid
	      Inform the flush(8) server that the message with	the  specified
	      queue ID is queued for the specified destination.

       send_site sitename
	      Request delivery of mail that is queued for the specified	desti-
	      nation.

       send_file queueid
	      Request delivery of the specified	deferred message.

       refresh
	      Refresh non-empty	per-destination	logfiles that were not read in
	      $fast_flush_refresh_time hours, by simulating send requests (see
	      above) for the corresponding destinations.

	      Delete empty per-destination logfiles that were not  updated  in
	      $fast_flush_purge_time days.

	      This request completes in	the background.

       purge  Do a refresh for all per-destination logfiles.

SECURITY
       The  flush(8) server is not security-sensitive. It does not talk	to the
       network,	and it does not	talk to	local users.  The  fast	 flush	server
       can run chrooted	at fixed low privilege.

DIAGNOSTICS
       Problems	and transactions are logged to syslogd(8).

BUGS
       Fast flush logfiles are truncated only after a "send" request, not when
       mail is actually	delivered, and therefore can  accumulate  outdated  or
       redundant data. In order	to maintain sanity, "refresh" must be executed
       periodically. This can be automated with	a suitable wakeup  timer  set-
       ting in the master.cf configuration file.

       Upon  receipt of	a request to deliver mail for an eligible destination,
       the flush(8) server requests delivery of	all messages that  are	listed
       in  that	 destination's	logfile, regardless of the recipients of those
       messages. This is not an	issue for mail that is sent to a relay_domains
       destination  because such mail typically	only has recipients in one do-
       main.

CONFIGURATION PARAMETERS
       Changes to main.cf are picked up	automatically  as  flush(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.

       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.

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

       fast_flush_refresh_time (12h)
	      The time after which  a  non-empty  but  unread  per-destination
	      "fast flush" logfile needs to be refreshed.

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

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

       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.

       parent_domain_matches_subdomains	(see 'postconf -d' output)
	      What Postfix features match subdomains of	"domain.tld" automati-
	      cally, instead of	requiring an explicit ".domain.tld" pattern.

       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.

       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".

FILES
       /var/spool/postfix/flush, "fast flush" logfiles.

SEE ALSO
       smtpd(8), SMTP server
       qmgr(8),	queue manager
       postconf(5), configuration parameters
       master(5), generic daemon options
       master(8), process manager
       syslogd(8), system logging

README FILES
       Use "postconf readme_directory" or "postconf html_directory" to	locate
       this information.
       ETRN_README, Postfix ETRN howto

LICENSE
       The Secure Mailer license must be distributed with this software.

HISTORY
       This service was	introduced with	Postfix	version	1.0.

AUTHOR(S)
       Wietse Venema
       IBM T.J.	Watson Research
       P.O. Box	704
       Yorktown	Heights, NY 10598, USA

								      FLUSH(8)

NAME | SYNOPSIS | DESCRIPTION | SECURITY | DIAGNOSTICS | BUGS | CONFIGURATION PARAMETERS | FILES | SEE ALSO | README FILES | LICENSE | HISTORY | AUTHOR(S)

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