flush(8) - man - phpman

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FLUSH(8postfix) FLUSH(8postfix)

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 de‐
ferred 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 parame‐
ter, 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_re‐‐
fresh_time hours, by simulating send requests (see above) for the corresponding desti‐
nations.

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) or postlogd(8).

BUGS
Fast flush logfiles are truncated only after a "send" request, not when mail is actually de‐
livered, and therefore can accumulate outdated or redundant data. In order to maintain san‐
ity, "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 re‐‐
lay_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 ter‐
minated 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 exam‐
ple, "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.

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

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

FLUSH(8postfix)