1OQMGR(8) System Manager's Manual OQMGR(8)
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6 oqmgr - old Postfix queue manager
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9 oqmgr [generic Postfix daemon options]
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12 The oqmgr(8) daemon awaits the arrival of incoming mail and arranges
13 for its delivery via Postfix delivery processes. The actual mail rout‐
14 ing strategy is delegated to the trivial-rewrite(8) daemon. This pro‐
15 gram expects to be run from the master(8) process manager.
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17 Mail addressed to the local double-bounce address is logged and dis‐
18 carded. This stops potential loops caused by undeliverable bounce
19 notifications.
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22 The oqmgr(8) daemon maintains the following queues:
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24 incoming
25 Inbound mail from the network, or mail picked up by the local
26 pickup(8) agent from the maildrop directory.
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28 active Messages that the queue manager has opened for delivery. Only a
29 limited number of messages is allowed to enter the active queue
30 (leaky bucket strategy, for a fixed delivery rate).
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32 deferred
33 Mail that could not be delivered upon the first attempt. The
34 queue manager implements exponential backoff by doubling the
35 time between delivery attempts.
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37 corrupt
38 Unreadable or damaged queue files are moved here for inspection.
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40 hold Messages that are kept "on hold" are kept here until someone
41 sets them free.
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44 The oqmgr(8) daemon keeps an eye on per-message delivery status reports
45 in the following directories. Each status report file has the same name
46 as the corresponding message file:
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48 bounce Per-recipient status information about why mail is bounced.
49 These files are maintained by the bounce(8) daemon.
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51 defer Per-recipient status information about why mail is delayed.
52 These files are maintained by the defer(8) daemon.
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54 trace Per-recipient status information as requested with the Postfix
55 "sendmail -v" or "sendmail -bv" command. These files are main‐
56 tained by the trace(8) daemon.
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58 The oqmgr(8) daemon is responsible for asking the bounce(8), defer(8)
59 or trace(8) daemons to send delivery reports.
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62 The queue manager implements a variety of strategies for either opening
63 queue files (input) or for message delivery (output).
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65 leaky bucket
66 This strategy limits the number of messages in the active queue
67 and prevents the queue manager from running out of memory under
68 heavy load.
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70 fairness
71 When the active queue has room, the queue manager takes one mes‐
72 sage from the incoming queue and one from the deferred queue.
73 This prevents a large mail backlog from blocking the delivery of
74 new mail.
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76 slow start
77 This strategy eliminates "thundering herd" problems by slowly
78 adjusting the number of parallel deliveries to the same destina‐
79 tion.
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81 round robin
82 The queue manager sorts delivery requests by destination.
83 Round-robin selection prevents one destination from dominating
84 deliveries to other destinations.
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86 exponential backoff
87 Mail that cannot be delivered upon the first attempt is
88 deferred. The time interval between delivery attempts is dou‐
89 bled after each attempt.
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91 destination status cache
92 The queue manager avoids unnecessary delivery attempts by main‐
93 taining a short-term, in-memory list of unreachable destina‐
94 tions.
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97 On an idle system, the queue manager waits for the arrival of trigger
98 events, or it waits for a timer to go off. A trigger is a one-byte mes‐
99 sage. Depending on the message received, the queue manager performs
100 one of the following actions (the message is followed by the symbolic
101 constant used internally by the software):
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103 D (QMGR_REQ_SCAN_DEFERRED)
104 Start a deferred queue scan. If a deferred queue scan is
105 already in progress, that scan will be restarted as soon as it
106 finishes.
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108 I (QMGR_REQ_SCAN_INCOMING)
109 Start an incoming queue scan. If an incoming queue scan is
110 already in progress, that scan will be restarted as soon as it
111 finishes.
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113 A (QMGR_REQ_SCAN_ALL)
114 Ignore deferred queue file time stamps. The request affects the
115 next deferred queue scan.
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117 F (QMGR_REQ_FLUSH_DEAD)
118 Purge all information about dead transports and destinations.
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120 W (TRIGGER_REQ_WAKEUP)
121 Wakeup call, This is used by the master server to instantiate
122 servers that should not go away forever. The action is to start
123 an incoming queue scan.
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125 The oqmgr(8) daemon reads an entire buffer worth of triggers. Multiple
126 identical trigger requests are collapsed into one, and trigger requests
127 are sorted so that A and F precede D and I. Thus, in order to force a
128 deferred queue run, one would request A F D; in order to notify the
129 queue manager of the arrival of new mail one would request I.
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132 RFC 3463 (Enhanced status codes)
133 RFC 3464 (Delivery status notifications)
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136 The oqmgr(8) daemon is not security sensitive. It reads single-charac‐
137 ter messages from untrusted local users, and thus may be susceptible to
138 denial of service attacks. The oqmgr(8) daemon does not talk to the
139 outside world, and it can be run at fixed low privilege in a chrooted
140 environment.
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143 Problems and transactions are logged to the syslog(8) daemon. Cor‐
144 rupted message files are saved to the corrupt queue for further inspec‐
145 tion.
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147 Depending on the setting of the notify_classes parameter, the postmas‐
148 ter is notified of bounces and of other trouble.
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151 A single queue manager process has to compete for disk access with mul‐
152 tiple front-end processes such as cleanup(8). A sudden burst of inbound
153 mail can negatively impact outbound delivery rates.
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156 Changes to main.cf are not picked up automatically, as oqmgr(8) is a
157 persistent process. Use the command "postfix reload" after a configura‐
158 tion change.
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160 The text below provides only a parameter summary. See postconf(5) for
161 more details including examples.
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163 In the text below, transport is the first field in a master.cf entry.
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166 Available before Postfix version 2.5:
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168 allow_min_user (no)
169 Allow a sender or recipient address to have `-' as the first
170 character.
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172 Available with Postfix version 2.7 and later:
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174 default_filter_nexthop (empty)
175 When a content_filter or FILTER request specifies no explicit
176 next-hop destination, use $default_filter_nexthop instead; when
177 that value is empty, use the domain in the recipient address.
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180 qmgr_clog_warn_time (300s)
181 The minimal delay between warnings that a specific destination
182 is clogging up the Postfix active queue.
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184 qmgr_message_active_limit (20000)
185 The maximal number of messages in the active queue.
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187 qmgr_message_recipient_limit (20000)
188 The maximal number of recipients held in memory by the Postfix
189 queue manager, and the maximal size of the short-term, in-memory
190 "dead" destination status cache.
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193 qmgr_fudge_factor (100)
194 Obsolete feature: the percentage of delivery resources that a
195 busy mail system will use up for delivery of a large mailing
196 list message.
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198 initial_destination_concurrency (5)
199 The initial per-destination concurrency level for parallel
200 delivery to the same destination.
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202 default_destination_concurrency_limit (20)
203 The default maximal number of parallel deliveries to the same
204 destination.
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206 transport_destination_concurrency_limit ($default_destination_concur‐
207 rency_limit)
208 Idem, for delivery via the named message transport.
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210 Available in Postfix version 2.5 and later:
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212 transport_initial_destination_concurrency ($initial_destination_concur‐
213 rency)
214 Initial concurrency for delivery via the named message trans‐
215 port.
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217 default_destination_concurrency_failed_cohort_limit (1)
218 How many pseudo-cohorts must suffer connection or handshake
219 failure before a specific destination is considered unavailable
220 (and further delivery is suspended).
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222 transport_destination_concurrency_failed_cohort_limit ($default_desti‐
223 nation_concurrency_failed_cohort_limit)
224 Idem, for delivery via the named message transport.
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226 default_destination_concurrency_negative_feedback (1)
227 The per-destination amount of delivery concurrency negative
228 feedback, after a delivery completes with a connection or hand‐
229 shake failure.
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231 transport_destination_concurrency_negative_feedback ($default_destina‐
232 tion_concurrency_negative_feedback)
233 Idem, for delivery via the named message transport.
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235 default_destination_concurrency_positive_feedback (1)
236 The per-destination amount of delivery concurrency positive
237 feedback, after a delivery completes without connection or hand‐
238 shake failure.
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240 transport_destination_concurrency_positive_feedback ($default_destina‐
241 tion_concurrency_positive_feedback)
242 Idem, for delivery via the named message transport.
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244 destination_concurrency_feedback_debug (no)
245 Make the queue manager's feedback algorithm verbose for perfor‐
246 mance analysis purposes.
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249 default_destination_recipient_limit (50)
250 The default maximal number of recipients per message delivery.
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252 transport_destination_recipient_limit
253 Idem, for delivery via the named message transport.
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256 minimal_backoff_time (300s)
257 The minimal time between attempts to deliver a deferred message;
258 prior to Postfix 2.4 the default value was 1000s.
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260 maximal_backoff_time (4000s)
261 The maximal time between attempts to deliver a deferred message.
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263 maximal_queue_lifetime (5d)
264 The maximal time a message is queued before it is sent back as
265 undeliverable.
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267 queue_run_delay (300s)
268 The time between deferred queue scans by the queue manager;
269 prior to Postfix 2.4 the default value was 1000s.
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271 transport_retry_time (60s)
272 The time between attempts by the Postfix queue manager to con‐
273 tact a malfunctioning message delivery transport.
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275 Available in Postfix version 2.1 and later:
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277 bounce_queue_lifetime (5d)
278 The maximal time a bounce message is queued before it is consid‐
279 ered undeliverable.
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281 Available in Postfix version 2.5 and later:
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283 default_destination_rate_delay (0s)
284 The default amount of delay that is inserted between individual
285 deliveries to the same destination; the resulting behavior
286 depends on the value of the corresponding per-destination recip‐
287 ient limit.
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289 transport_destination_rate_delay $default_destination_rate_delay
290 Idem, for delivery via the named message transport.
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293 qmgr_daemon_timeout (1000s)
294 How much time a Postfix queue manager process may take to handle
295 a request before it is terminated by a built-in watchdog timer.
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297 qmgr_ipc_timeout (60s)
298 The time limit for the queue manager to send or receive informa‐
299 tion over an internal communication channel.
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302 config_directory (see 'postconf -d' output)
303 The default location of the Postfix main.cf and master.cf con‐
304 figuration files.
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306 defer_transports (empty)
307 The names of message delivery transports that should not deliver
308 mail unless someone issues "sendmail -q" or equivalent.
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310 delay_logging_resolution_limit (2)
311 The maximal number of digits after the decimal point when log‐
312 ging sub-second delay values.
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314 helpful_warnings (yes)
315 Log warnings about problematic configuration settings, and pro‐
316 vide helpful suggestions.
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318 process_id (read-only)
319 The process ID of a Postfix command or daemon process.
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321 process_name (read-only)
322 The process name of a Postfix command or daemon process.
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324 queue_directory (see 'postconf -d' output)
325 The location of the Postfix top-level queue directory.
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327 syslog_facility (mail)
328 The syslog facility of Postfix logging.
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330 syslog_name (see 'postconf -d' output)
331 The mail system name that is prepended to the process name in
332 syslog records, so that "smtpd" becomes, for example, "post‐
333 fix/smtpd".
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336 /var/spool/postfix/incoming, incoming queue
337 /var/spool/postfix/active, active queue
338 /var/spool/postfix/deferred, deferred queue
339 /var/spool/postfix/bounce, non-delivery status
340 /var/spool/postfix/defer, non-delivery status
341 /var/spool/postfix/trace, delivery status
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344 trivial-rewrite(8), address routing
345 bounce(8), delivery status reports
346 postconf(5), configuration parameters
347 master(5), generic daemon options
348 master(8), process manager
349 syslogd(8), system logging
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352 Use "postconf readme_directory" or "postconf html_directory" to locate
353 this information.
354 QSHAPE_README, Postfix queue analysis
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357 The Secure Mailer license must be distributed with this software.
358
360 Wietse Venema
361 IBM T.J. Watson Research
362 P.O. Box 704
363 Yorktown Heights, NY 10598, USA
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367 OQMGR(8)