# flush(8) - man - phpman [FLUSH(8postfix)](https://www.chedong.com/phpMan.php/man/FLUSH/8postfix/markdown) [FLUSH(8postfix)](https://www.chedong.com/phpMan.php/man/FLUSH/8postfix/markdown) ## NAME flush - Postfix fast flush server ## SYNOPSIS **flush** [generic Postfix daemon options] ## DESCRIPTION The [**flush**(8)](https://www.chedong.com/phpMan.php/man/flush/8/markdown) 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)](https://www.chedong.com/phpMan.php/man/master/8/markdown) 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 **$relay**___**domains**. This server implements the following requests: **add** _sitename_ _queueid_ Inform the [**flush**(8)](https://www.chedong.com/phpMan.php/man/flush/8/markdown) server that the message with the specified queue ID is queued for the specified destination. **send**___**site** _sitename_ Request delivery of mail that is queued for the specified destination. **send**___**file** _queueid_ Request delivery of the specified deferred message. ### refresh Refresh non-empty per-destination logfiles that were not read in **$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)](https://www.chedong.com/phpMan.php/man/flush/8/markdown) 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)](https://www.chedong.com/phpMan.php/man/syslogd/8/markdown) or [**postlogd**(8)](https://www.chedong.com/phpMan.php/man/postlogd/8/markdown). ## 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)](https://www.chedong.com/phpMan.php/man/flush/8/markdown) 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)](https://www.chedong.com/phpMan.php/man/flush/8/markdown) 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)](https://www.chedong.com/phpMan.php/man/postconf/5/markdown) 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)](https://www.chedong.com/phpMan.php/man/smtpd/8/markdown), SMTP server [qmgr(8)](https://www.chedong.com/phpMan.php/man/qmgr/8/markdown), queue manager [postconf(5)](https://www.chedong.com/phpMan.php/man/postconf/5/markdown), configuration parameters [master(5)](https://www.chedong.com/phpMan.php/man/master/5/markdown), generic daemon options [master(8)](https://www.chedong.com/phpMan.php/man/master/8/markdown), process manager [postlogd(8)](https://www.chedong.com/phpMan.php/man/postlogd/8/markdown), Postfix logging [syslogd(8)](https://www.chedong.com/phpMan.php/man/syslogd/8/markdown), 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)](https://www.chedong.com/phpMan.php/man/FLUSH/8postfix/markdown)