FLUSH(8)                                                              FLUSH(8)

       flush - Postfix fast flush server

       flush [generic Postfix daemon options]

       The flush(8) server maintains a record of deferred mail by
       destination.  This information is used to improve the per-
       formance of the SMTP ETRN request, and of its command-line
       equivalent, "sendmail -qR" or "postqueue -f".   This  pro-
       gram 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  truncated  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 eligible destinations. The list of eligible  des-
       tinations is specified with the fast_flush_domains config-
       uration parameter, which defaults to $relay_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

       send_site sitename
              Request delivery of mail that  is  queued  for  the
              specified destination.

       send_file queueid
              Request delivery of the specified deferred message.

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

       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 privi-

       Problems and transactions are logged to syslogd(8).

       Fast  flush  logfiles  are  truncated  only after a "send"
       request, not when mail is actually delivered,  and  there-
       fore  can  accumulate outdated or redundant data. In order
       to maintain sanity, "refresh" must  be  executed  periodi-
       cally.  This can be automated with a suitable wakeup timer
       setting 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 des-
       tination  because  such mail typically only has recipients
       in one domain.

       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 configuration files.

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

       fast_flush_domains ($relay_domains)
              Optional list of destinations that are eligible for
              per-destination  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

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

       ipc_timeout (3600s)
              The time limit for sending or receiving information
              over an internal 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 termi-
              nating voluntarily.

       parent_domain_matches_subdomains (see 'postconf  -d'  out-
              What   Postfix   features   match   subdomains   of
              "domain.tld" automatically, instead of requiring an
              explicit ".domain.tld" pattern.

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

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

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

       syslog_facility (mail)
              The syslog facility of Postfix logging.

       syslog_name (postfix)
              The  mail  system  name  that  is  prepended to the
              process name in syslog  records,  so  that  "smtpd"
              becomes, for example, "postfix/smtpd".

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

       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

       ETRN_README, Postfix ETRN howto

       The Secure Mailer license must be  distributed  with  this

       This service was introduced with Postfix version 1.0.

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