1FLUSH(8) System Manager's Manual FLUSH(8)
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6 flush - Postfix fast flush server
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9 flush [generic Postfix daemon options]
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12 The flush(8) server maintains a record of deferred mail by destination.
13 This information is used to improve the performance of the SMTP ETRN
14 request, and of its command-line equivalent, "sendmail -qR" or
15 "postqueue -f". This program expects to be run from the master(8)
16 process manager.
17 The record is implemented as a per-destination logfile with as contents
19 the queue IDs of deferred mail. A logfile is append-only, and is trun‐
20 cated when delivery is requested for the corresponding destination. A
21 destination is the part on the right-hand side of the right-most @ in
22 an email address.
23 Per-destination logfiles of deferred mail are maintained only for eli‐
25 gible destinations. The list of eligible destinations is specified with
26 the fast_flush_domains configuration parameter, which defaults to
27 $relay_domains.
28 This server implements the following requests:
30 add sitename queueid
32 Inform the flush(8) server that the message with the specified
33 queue ID is queued for the specified destination.
34 send_site sitename
36 Request delivery of mail that is queued for the specified desti‐
37 nation.
38 send_file queueid
40 Request delivery of the specified deferred message.
41 refresh
43 Refresh non-empty per-destination logfiles that were not read in
44 $fast_flush_refresh_time hours, by simulating send requests (see
45 above) for the corresponding destinations.
46 Delete empty per-destination logfiles that were not updated in
48 $fast_flush_purge_time days.
49 This request completes in the background.
51 purge Do a refresh for all per-destination logfiles.
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55 The flush(8) server is not security-sensitive. It does not talk to the
56 network, and it does not talk to local users. The fast flush server
57 can run chrooted at fixed low privilege.
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60 Problems and transactions are logged to syslogd(8).
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63 Fast flush logfiles are truncated only after a "send" request, not when
64 mail is actually delivered, and therefore can accumulate outdated or
65 redundant data. In order to maintain sanity, "refresh" must be executed
66 periodically. This can be automated with a suitable wakeup timer set‐
67 ting in the master.cf configuration file.
68 Upon receipt of a request to deliver mail for an eligible destination,
70 the flush(8) server requests delivery of all messages that are listed
71 in that destination's logfile, regardless of the recipients of those
72 messages. This is not an issue for mail that is sent to a relay_domains
73 destination because such mail typically only has recipients in one
74 domain.
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77 Changes to main.cf are picked up automatically as flush(8) processes
78 run for only a limited amount of time. Use the command "postfix reload"
79 to speed up a change.
80 The text below provides only a parameter summary. See postconf(5) for
82 more details including examples.
83 config_directory (see 'postconf -d' output)
85 The default location of the Postfix main.cf and master.cf con‐
86 figuration files.
87 daemon_timeout (18000s)
89 How much time a Postfix daemon process may take to handle a
90 request before it is terminated by a built-in watchdog timer.
91 fast_flush_domains ($relay_domains)
93 Optional list of destinations that are eligible for per-destina‐
94 tion logfiles with mail that is queued to those destinations.
95 fast_flush_refresh_time (12h)
97 The time after which a non-empty but unread per-destination
98 "fast flush" logfile needs to be refreshed.
99 fast_flush_purge_time (7d)
101 The time after which an empty per-destination "fast flush" log‐
102 file is deleted.
103 ipc_timeout (3600s)
105 The time limit for sending or receiving information over an
106 internal communication channel.
107 max_idle (100s)
109 The maximum amount of time that an idle Postfix daemon process
110 waits for an incoming connection before terminating voluntarily.
111 max_use (100)
113 The maximal number of incoming connections that a Postfix daemon
114 process will service before terminating voluntarily.
115 parent_domain_matches_subdomains (see 'postconf -d' output)
117 What Postfix features match subdomains of "domain.tld" automati‐
118 cally, instead of requiring an explicit ".domain.tld" pattern.
119 process_id (read-only)
121 The process ID of a Postfix command or daemon process.
122 process_name (read-only)
124 The process name of a Postfix command or daemon process.
125 queue_directory (see 'postconf -d' output)
127 The location of the Postfix top-level queue directory.
128 syslog_facility (mail)
130 The syslog facility of Postfix logging.
131 syslog_name (postfix)
133 The mail system name that is prepended to the process name in
134 syslog records, so that "smtpd" becomes, for example, "post‐
135 fix/smtpd".
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138 /var/spool/postfix/flush, "fast flush" logfiles.
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141 smtpd(8), SMTP server
142 qmgr(8), queue manager
143 postconf(5), configuration parameters
144 master(5), generic daemon options
145 master(8), process manager
146 syslogd(8), system logging
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149 Use "postconf readme_directory" or "postconf html_directory" to locate
150 this information.
151 ETRN_README, Postfix ETRN howto
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154 The Secure Mailer license must be distributed with this software.
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157 This service was introduced with Postfix version 1.0.
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160 Wietse Venema
161 IBM T.J. Watson Research
162 P.O. Box 704
163 Yorktown Heights, NY 10598, USA
164 FLUSH(8)