1OQMGR(8) System Manager's Manual OQMGR(8)
2
6 oqmgr - old Postfix queue manager
7
9 oqmgr [generic Postfix daemon options]
10
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.
16 Mail addressed to the local double-bounce address is logged and dis‐
18 carded. This stops potential loops caused by undeliverable bounce
19 notifications.
20
22 The oqmgr(8) daemon maintains the following queues:
23 incoming
25 Inbound mail from the network, or mail picked up by the local
26 pickup(8) agent from the maildrop directory.
27 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).
31 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.
36 corrupt
38 Unreadable or damaged queue files are moved here for inspection.
39 hold Messages that are kept "on hold" are kept here until someone
41 sets them free.
42
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:
47 bounce Per-recipient status information about why mail is bounced.
49 These files are maintained by the bounce(8) daemon.
50 defer Per-recipient status information about why mail is delayed.
52 These files are maintained by the defer(8) daemon.
53 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.
57 The oqmgr(8) daemon is responsible for asking the bounce(8), defer(8)
59 or trace(8) daemons to send delivery reports.
60
62 The queue manager implements a variety of strategies for either opening
63 queue files (input) or for message delivery (output).
64 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.
69 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.
75 slow start
77 This strategy eliminates "thundering herd" problems by slowly
78 adjusting the number of parallel deliveries to the same destina‐
79 tion.
80 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.
85 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.
90 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.
95
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):
102 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.
107 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.
112 A (QMGR_REQ_SCAN_ALL)
114 Ignore deferred queue file time stamps. The request affects the
115 next deferred queue scan.
116 F (QMGR_REQ_FLUSH_DEAD)
118 Purge all information about dead transports and destinations.
119 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.
124 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.
130
132 RFC 3463 (Enhanced status codes)
133 RFC 3464 (Delivery status notifications)
134
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.
141
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.
146 Depending on the setting of the notify_classes parameter, the postmas‐
148 ter is notified of bounces and of other trouble.
149
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.
154
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.
159 The text below provides only a parameter summary. See postconf(5) for
161 more details including examples.
162 In the text below, transport is the first field in a master.cf entry.
164
166 Available before Postfix version 2.5:
167 allow_min_user (no)
169 Allow a sender or recipient address to have `-' as the first
170 character.
171 Available with Postfix version 2.7 and later:
173 default_filter_nexthop (empty)
175 When a content_filter or FILTER request specifies no explicit
176 next-hop destination, use $default_filter_nexthop instead; when
177 that value is empty, use the domain in the recipient address.
178
180 qmgr_clog_warn_time (300s)
181 The minimal delay between warnings that a specific destination
182 is clogging up the Postfix active queue.
183 qmgr_message_active_limit (20000)
185 The maximal number of messages in the active queue.
186 qmgr_message_recipient_limit (20000)
188 The maximal number of recipients held in memory by the Postfix
189 queue manager, and the maximal size of the short-term, in-memory
190 "dead" destination status cache.
191
193 qmgr_fudge_factor (100)
194 Obsolete feature: the percentage of delivery resources that a
195 busy mail system will use up for delivery of a large mailing
196 list message.
197 initial_destination_concurrency (5)
199 The initial per-destination concurrency level for parallel
200 delivery to the same destination.
201 default_destination_concurrency_limit (20)
203 The default maximal number of parallel deliveries to the same
204 destination.
205 transport_destination_concurrency_limit ($default_destination_concur‐
207 rency_limit)
208 A transport-specific override for the default_destination_con‐
209 currency_limit parameter value, where transport is the master.cf
210 name of the message delivery transport.
211 Available in Postfix version 2.5 and later:
213 transport_initial_destination_concurrency ($initial_destination_concur‐
215 rency)
216 A transport-specific override for the initial_destination_con‐
217 currency parameter value, where transport is the master.cf name
218 of the message delivery transport.
219 default_destination_concurrency_failed_cohort_limit (1)
221 How many pseudo-cohorts must suffer connection or handshake
222 failure before a specific destination is considered unavailable
223 (and further delivery is suspended).
224 transport_destination_concurrency_failed_cohort_limit ($default_desti‐
226 nation_concurrency_failed_cohort_limit)
227 A transport-specific override for the default_destination_con‐
228 currency_failed_cohort_limit parameter value, where transport is
229 the master.cf name of the message delivery transport.
230 default_destination_concurrency_negative_feedback (1)
232 The per-destination amount of delivery concurrency negative
233 feedback, after a delivery completes with a connection or hand‐
234 shake failure.
235 transport_destination_concurrency_negative_feedback ($default_destina‐
237 tion_concurrency_negative_feedback)
238 A transport-specific override for the default_destination_con‐
239 currency_negative_feedback parameter value, where transport is
240 the master.cf name of the message delivery transport.
241 default_destination_concurrency_positive_feedback (1)
243 The per-destination amount of delivery concurrency positive
244 feedback, after a delivery completes without connection or hand‐
245 shake failure.
246 transport_destination_concurrency_positive_feedback ($default_destina‐
248 tion_concurrency_positive_feedback)
249 A transport-specific override for the default_destination_con‐
250 currency_positive_feedback parameter value, where transport is
251 the master.cf name of the message delivery transport.
252 destination_concurrency_feedback_debug (no)
254 Make the queue manager's feedback algorithm verbose for perfor‐
255 mance analysis purposes.
256
258 default_destination_recipient_limit (50)
259 The default maximal number of recipients per message delivery.
260 transport_destination_recipient_limit ($default_destination_recipi‐
262 ent_limit)
263 A transport-specific override for the default_destination_recip‐
264 ient_limit parameter value, where transport is the master.cf
265 name of the message delivery transport.
266
268 minimal_backoff_time (300s)
269 The minimal time between attempts to deliver a deferred message;
270 prior to Postfix 2.4 the default value was 1000s.
271 maximal_backoff_time (4000s)
273 The maximal time between attempts to deliver a deferred message.
274 maximal_queue_lifetime (5d)
276 Consider a message as undeliverable, when delivery fails with a
277 temporary error, and the time in the queue has reached the maxi‐
278 mal_queue_lifetime limit.
279 queue_run_delay (300s)
281 The time between deferred queue scans by the queue manager;
282 prior to Postfix 2.4 the default value was 1000s.
283 transport_retry_time (60s)
285 The time between attempts by the Postfix queue manager to con‐
286 tact a malfunctioning message delivery transport.
287 Available in Postfix version 2.1 and later:
289 bounce_queue_lifetime (5d)
291 Consider a bounce message as undeliverable, when delivery fails
292 with a temporary error, and the time in the queue has reached
293 the bounce_queue_lifetime limit.
294 Available in Postfix version 2.5 and later:
296 default_destination_rate_delay (0s)
298 The default amount of delay that is inserted between individual
299 deliveries to the same destination; the resulting behavior
300 depends on the value of the corresponding per-destination recip‐
301 ient limit.
302 transport_destination_rate_delay ($default_destination_rate_delay)
304 A transport-specific override for the default_destina‐
305 tion_rate_delay parameter value, where transport is the mas‐
306 ter.cf name of the message delivery transport.
307 Available in Postfix version 3.1 and later:
309 default_transport_rate_delay (0s)
311 The default amount of delay that is inserted between individual
312 deliveries over the same message delivery transport, regardless
313 of destination.
314 transport_transport_rate_delay ($default_transport_rate_delay)
316 A transport-specific override for the default_trans‐
317 port_rate_delay parameter value, where the initial transport in
318 the parameter name is the master.cf name of the message delivery
319 transport.
320
322 qmgr_daemon_timeout (1000s)
323 How much time a Postfix queue manager process may take to handle
324 a request before it is terminated by a built-in watchdog timer.
325 qmgr_ipc_timeout (60s)
327 The time limit for the queue manager to send or receive informa‐
328 tion over an internal communication channel.
329 Available in Postfix version 3.1 and later:
331 address_verify_pending_request_limit (see 'postconf -d' output)
333 A safety limit that prevents address verification requests from
334 overwhelming the Postfix queue.
335
337 config_directory (see 'postconf -d' output)
338 The default location of the Postfix main.cf and master.cf con‐
339 figuration files.
340 defer_transports (empty)
342 The names of message delivery transports that should not deliver
343 mail unless someone issues "sendmail -q" or equivalent.
344 delay_logging_resolution_limit (2)
346 The maximal number of digits after the decimal point when log‐
347 ging sub-second delay values.
348 helpful_warnings (yes)
350 Log warnings about problematic configuration settings, and pro‐
351 vide helpful suggestions.
352 process_id (read-only)
354 The process ID of a Postfix command or daemon process.
355 process_name (read-only)
357 The process name of a Postfix command or daemon process.
358 queue_directory (see 'postconf -d' output)
360 The location of the Postfix top-level queue directory.
361 syslog_facility (mail)
363 The syslog facility of Postfix logging.
364 syslog_name (see 'postconf -d' output)
366 A prefix that is prepended to the process name in syslog
367 records, so that, for example, "smtpd" becomes "prefix/smtpd".
368 Available in Postfix version 3.0 and later:
370 confirm_delay_cleared (no)
372 After sending a "your message is delayed" notification, inform
373 the sender when the delay clears up.
374 Available in Postfix 3.3 and later:
376 service_name (read-only)
378 The master.cf service name of a Postfix daemon process.
379
381 /var/spool/postfix/incoming, incoming queue
382 /var/spool/postfix/active, active queue
383 /var/spool/postfix/deferred, deferred queue
384 /var/spool/postfix/bounce, non-delivery status
385 /var/spool/postfix/defer, non-delivery status
386 /var/spool/postfix/trace, delivery status
387
389 trivial-rewrite(8), address routing
390 bounce(8), delivery status reports
391 postconf(5), configuration parameters
392 master(5), generic daemon options
393 master(8), process manager
394 syslogd(8), system logging
395
397 Use "postconf readme_directory" or "postconf html_directory" to locate
398 this information.
399 QSHAPE_README, Postfix queue analysis
400
402 The Secure Mailer license must be distributed with this software.
403
405 Wietse Venema
406 IBM T.J. Watson Research
407 P.O. Box 704
408 Yorktown Heights, NY 10598, USA
409 Wietse Venema
411 Google, Inc.
412 111 8th Avenue
413 New York, NY 10011, USA
414 OQMGR(8)