NAME

flush - Postfix fast flush server

SYNOPSIS


fflluusshh [generic Postfix daemon options]

DESCRIPTION

The fflluusshh(8) server maintains a record of deferred mail by destination. This information is used to improve the performance of the SMTP EETTRRNN request, and of its command-line equivalent, "sseennddmmaaiill --qqRR" or "ppoossttqquueeuuee --ff". This program expects to be run from the mmaasstteerr(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 ffaasstt__fflluusshh__ddoommaaiinnss configuration parameter, which defaults to $$rreellaayy__ddoommaaiinnss.

This server implements the following requests:

aadddd _s_i_t_e_n_a_m_e _q_u_e_u_e_i_d Inform the fflluusshh(8) server that the message with the specified
queue ID is queued for the specified destination.
sseenndd__ssiittee _s_i_t_e_n_a_m_e Request delivery of mail that is queued for the specified
destination.
sseenndd__ffiillee _q_u_e_u_e_i_d Request delivery of the specified deferred message.
rreeffrreesshh Refresh non-empty per-destination logfiles that were not read in
$$ffaasstt__fflluusshh__rreeffrreesshh__ttiimmee hours, by simulating send requests (see above) for the corresponding destinations.

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

This request completes in the background.
ppuurrggee Do a rreeffrreesshh for all per-destination logfiles.

SECURITY



The fflluusshh(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 ssyyssllooggdd(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logfiles are truncated only after a "send" request, not when mail is actually delivered, and therefore can accumulate outdated or redundant data.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 mmaasstteerr..ccff configuration file.

Upon receipt of a request to deliver mail for an eligible destination, the fflluusshh(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 rreellaayy__ddoommaaiinnss destination because such mail typically only has recipients in one domain.

CONFIGURATION PARAMETERS



Changes to mmaaiinn..ccff are picked up automatically as fflluusshh(8)
processes run for only a limited amount of time. Use the command
"ppoossttffiixx rreellooaadd" to speed up a change.
        

The text below provides only a parameter summary. See ppoossttccoonnff(5) for more details including examples.

ccoonnffiigg__ddiirreeccttoorryy ((sseeee ''ppoossttccoonnff --dd'' oouuttppuutt)) The default location of the Postfix main.cf and master.cf
configuration files.
ddaaeemmoonn__ttiimmeeoouutt ((1188000000ss)) How much time a Postfix daemon process may take to handle a
request before it is terminated by a built-in watchdog timer.
ffaasstt__fflluusshh__ddoommaaiinnss (($$rreellaayy__ddoommaaiinnss)) Optional list of destinations that are eligible for per-destination
logfiles with mail that is queued to those destinations.
ffaasstt__fflluusshh__rreeffrreesshh__ttiimmee ((1122hh)) The time after which a non-empty but unread per-destination "fast
flush" logfile needs to be refreshed.
ffaasstt__fflluusshh__ppuurrggee__ttiimmee ((77dd)) The time after which an empty per-destination "fast flush" logfile
is deleted.
iippcc__ttiimmeeoouutt ((33660000ss)) The time limit for sending or receiving information over an internal
communication channel.
mmaaxx__iiddllee ((110000ss)) The maximum amount of time that an idle Postfix daemon process waits
for an incoming connection before terminating voluntarily.
mmaaxx__uussee ((110000)) The maximal number of incoming connections that a Postfix daemon
process will service before terminating voluntarily.
ppaarreenntt__ddoommaaiinn__mmaattcchheess__ssuubbddoommaaiinnss ((sseeee ''ppoossttccoonnff --dd'' oouuttppuutt)) What Postfix features match subdomains of "domain.tld" automatically,
instead of requiring an explicit ".domain.tld" pattern.
pprroocceessss__iidd ((rreeaadd--oonnllyy)) The process ID of a Postfix command or daemon process.
pprroocceessss__nnaammee ((rreeaadd--oonnllyy)) The process name of a Postfix command or daemon process.
qquueeuuee__ddiirreeccttoorryy ((sseeee ''ppoossttccoonnff --dd'' oouuttppuutt)) The location of the Postfix top-level queue directory.
ssyysslloogg__ffaacciilliittyy ((mmaaiill)) The syslog facility of Postfix logging.
ssyysslloogg__nnaammee ((sseeee ''ppoossttccoonnff --dd'' oouuttppuutt)) The mail system name that is prepended to the process name in syslog
records, so that "smtpd" becomes, for example, "postfix/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 "ppoossttccoonnff rreeaaddmmee__ddiirreeccttoorryy" or
"ppoossttccoonnff hhttmmll__ddiirreeccttoorryy" 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