1OQMGR(8) System Manager's Manual OQMGR(8)
2
6 oqmgr - old Postfix queue manager
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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
173 qmgr_clog_warn_time (300s)
174 The minimal delay between warnings that a specific destination
175 is clogging up the Postfix active queue.
176 qmgr_message_active_limit (20000)
178 The maximal number of messages in the active queue.
179 qmgr_message_recipient_limit (20000)
181 The maximal number of recipients held in memory by the Postfix
182 queue manager, and the maximal size of the size of the short-
183 term, in-memory "dead" destination status cache.
184
186 qmgr_fudge_factor (100)
187 Obsolete feature: the percentage of delivery resources that a
188 busy mail system will use up for delivery of a large mailing
189 list message.
190 initial_destination_concurrency (5)
192 The initial per-destination concurrency level for parallel
193 delivery to the same destination.
194 default_destination_concurrency_limit (20)
196 The default maximal number of parallel deliveries to the same
197 destination.
198 transport_destination_concurrency_limit ($default_destination_concur‐
200 rency_limit)
201 Idem, for delivery via the named message transport.
202 Available in Postfix version 2.5 and later:
204 transport_initial_destination_concurrency ($initial_destination_concur‐
206 rency)
207 Initial concurrency for delivery via the named message trans‐
208 port.
209 default_destination_concurrency_failed_cohort_limit (1)
211 How many pseudo-cohorts must suffer connection or handshake
212 failure before a specific destination is considered unavailable
213 (and further delivery is suspended).
214 transport_destination_concurrency_failed_cohort_limit ($default_desti‐
216 nation_concurrency_failed_cohort_limit)
217 Idem, for delivery via the named message transport.
218 default_destination_concurrency_negative_feedback (1)
220 The per-destination amount of delivery concurrency negative
221 feedback, after a delivery completes with a connection or hand‐
222 shake failure.
223 transport_destination_concurrency_negative_feedback ($default_destina‐
225 tion_concurrency_negative_feedback)
226 Idem, for delivery via the named message transport.
227 default_destination_concurrency_positive_feedback (1)
229 The per-destination amount of delivery concurrency positive
230 feedback, after a delivery completes without connection or hand‐
231 shake failure.
232 transport_destination_concurrency_positive_feedback ($default_destina‐
234 tion_concurrency_positive_feedback)
235 Idem, for delivery via the named message transport.
236 destination_concurrency_feedback_debug (no)
238 Make the queue manager's feedback algorithm verbose for perfor‐
239 mance analysis purposes.
240
242 default_destination_recipient_limit (50)
243 The default maximal number of recipients per message delivery.
244 transport_destination_recipient_limit
246 Idem, for delivery via the named message transport.
247
249 minimal_backoff_time (300s)
250 The minimal time between attempts to deliver a deferred message;
251 prior to Postfix 2.4 the default value was 1000s.
252 maximal_backoff_time (4000s)
254 The maximal time between attempts to deliver a deferred message.
255 maximal_queue_lifetime (5d)
257 The maximal time a message is queued before it is sent back as
258 undeliverable.
259 queue_run_delay (300s)
261 The time between deferred queue scans by the queue manager;
262 prior to Postfix 2.4 the default value was 1000s.
263 transport_retry_time (60s)
265 The time between attempts by the Postfix queue manager to con‐
266 tact a malfunctioning message delivery transport.
267 Available in Postfix version 2.1 and later:
269 bounce_queue_lifetime (5d)
271 The maximal time a bounce message is queued before it is consid‐
272 ered undeliverable.
273 Available in Postfix version 2.5 and later:
275 default_destination_rate_delay (0s)
277 The default amount of delay that is inserted between individual
278 deliveries to the same destination; with per-destination recipi‐
279 ent limit > 1, a destination is a domain, otherwise it is a
280 recipient.
281 transport_destination_rate_delay $default_destination_rate_delay
283 Idem, for delivery via the named message transport.
284
286 config_directory (see 'postconf -d' output)
287 The default location of the Postfix main.cf and master.cf con‐
288 figuration files.
289 defer_transports (empty)
291 The names of message delivery transports that should not deliver
292 mail unless someone issues "sendmail -q" or equivalent.
293 delay_logging_resolution_limit (2)
295 The maximal number of digits after the decimal point when log‐
296 ging sub-second delay values.
297 helpful_warnings (yes)
299 Log warnings about problematic configuration settings, and pro‐
300 vide helpful suggestions.
301 ipc_timeout (3600s)
303 The time limit for sending or receiving information over an
304 internal communication channel.
305 process_id (read-only)
307 The process ID of a Postfix command or daemon process.
308 process_name (read-only)
310 The process name of a Postfix command or daemon process.
311 queue_directory (see 'postconf -d' output)
313 The location of the Postfix top-level queue directory.
314 syslog_facility (mail)
316 The syslog facility of Postfix logging.
317 syslog_name (see 'postconf -d' output)
319 The mail system name that is prepended to the process name in
320 syslog records, so that "smtpd" becomes, for example, "post‐
321 fix/smtpd".
322
324 /var/spool/postfix/incoming, incoming queue
325 /var/spool/postfix/active, active queue
326 /var/spool/postfix/deferred, deferred queue
327 /var/spool/postfix/bounce, non-delivery status
328 /var/spool/postfix/defer, non-delivery status
329 /var/spool/postfix/trace, delivery status
330
332 trivial-rewrite(8), address routing
333 bounce(8), delivery status reports
334 postconf(5), configuration parameters
335 master(5), generic daemon options
336 master(8), process manager
337 syslogd(8), system logging
338
340 Use "postconf readme_directory" or "postconf html_directory" to locate
341 this information.
342 QSHAPE_README, Postfix queue analysis
343
345 The Secure Mailer license must be distributed with this software.
346
348 Wietse Venema
349 IBM T.J. Watson Research
350 P.O. Box 704
351 Yorktown Heights, NY 10598, USA
352 OQMGR(8)