Ubuntu Manpage: flush - Postfix fast flush server

Provided by: postfix_3.3.0-1ubuntu0.4_amd64

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 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 destinations is specified with the fast_flush_domains configuration
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 destination.

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
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       delivered, and therefore can accumulate outdated or redundant data.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 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  destination  because  such mail typically only has recipients in one
       domain.

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 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 refreshed.

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 terminating voluntarily.

parent_domain_matches_subdomains (see 'postconf -d' output)
A list of Postfix features where the pattern "example.com" also matches subdomains
of example.com, instead of requiring an explicit ".example.com" 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)
A prefix that is prepended to the process name in syslog records, so that, for
example, "smtpd" becomes "prefix/smtpd".

Available in Postfix 3.3 and later:

service_name (read-only)
The master.cf service name of a Postfix daemon process.

FILES

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

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

       Wietse Venema
       Google, Inc.
       111 8th Avenue
       New York, NY 10011, USA

                                                                                  FLUSH(8postfix)