1PIPE(8) System Manager's Manual PIPE(8)
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6 pipe - Postfix delivery to external command
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9 pipe [generic Postfix daemon options] command_attributes...
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12 The pipe(8) daemon processes requests from the Postfix queue manager to
13 deliver messages to external commands. This program expects to be run
14 from the master(8) process manager.
15 Message attributes such as sender address, recipient address and
17 next-hop host name can be specified as command-line macros that are ex‐
18 panded before the external command is executed.
19 The pipe(8) daemon updates queue files and marks recipients as fin‐
21 ished, or it informs the queue manager that delivery should be tried
22 again at a later time. Delivery status reports are sent to the
23 bounce(8), defer(8) or trace(8) daemon as appropriate.
24
26 Some destinations cannot handle more than one recipient per delivery
27 request. Examples are pagers or fax machines. In addition, multi-re‐
28 cipient delivery is undesirable when prepending a Delivered-to: or
29 X-Original-To: message header.
30 To prevent Postfix from sending multiple recipients per delivery re‐
32 quest, specify
33 transport_destination_recipient_limit = 1
35 in the Postfix main.cf file, where transport is the name in the first
37 column of the Postfix master.cf entry for the pipe-based delivery
38 transport.
39
41 The external command attributes are given in the master.cf file at the
42 end of a service definition. The syntax is as follows:
43 chroot=pathname (optional)
45 Change the process root directory and working directory to the
46 named directory. This happens before switching to the privileges
47 specified with the user attribute, and before executing the op‐
48 tional directory=pathname directive. Delivery is deferred in
49 case of failure.
50 This feature is available as of Postfix 2.3.
52 directory=pathname (optional)
54 Change to the named directory before executing the external com‐
55 mand. The directory must be accessible for the user specified
56 with the user attribute (see below). The default working direc‐
57 tory is $queue_directory. Delivery is deferred in case of fail‐
58 ure.
59 This feature is available as of Postfix 2.2.
61 eol=string (optional, default: \n)
63 The output record delimiter. Typically one would use either \r\n
64 or \n. The usual C-style backslash escape sequences are recog‐
65 nized: \a \b \f \n \r \t \v \ddd (up to three octal digits) and
66 \\.
67 flags=BDFORXhqu.> (optional)
69 Optional message processing flags. By default, a message is
70 copied unchanged.
71 B Append a blank line at the end of each message. This is
73 required by some mail user agents that recognize "From "
74 lines only when preceded by a blank line.
75 D Prepend a "Delivered-To: recipient" message header with
77 the envelope recipient address. Note: for this to work,
78 the transport_destination_recipient_limit must be 1 (see
79 SINGLE-RECIPIENT DELIVERY above for details).
80 The D flag also enforces loop detection (Postfix 2.5 and
82 later): if a message already contains a Delivered-To:
83 header with the same recipient address, then the message
84 is returned as undeliverable. The address comparison is
85 case insensitive.
86 This feature is available as of Postfix 2.0.
88 F Prepend a "From sender time_stamp" envelope header to the
90 message content. This is expected by, for example, UUCP
91 software.
92 O Prepend an "X-Original-To: recipient" message header with
94 the recipient address as given to Postfix. Note: for this
95 to work, the transport_destination_recipient_limit must
96 be 1 (see SINGLE-RECIPIENT DELIVERY above for details).
97 This feature is available as of Postfix 2.0.
99 R Prepend a Return-Path: message header with the envelope
101 sender address.
102 X Indicate that the external command performs final deliv‐
104 ery. This flag affects the status reported in "success"
105 DSN (delivery status notification) messages, and changes
106 it from "relayed" into "delivered".
107 This feature is available as of Postfix 2.5.
109 h Fold the command-line $original_recipient and $recipient
111 address domain part (text to the right of the right-most
112 @ character) to lower case; fold the entire command-line
113 $domain and $nexthop host or domain information to lower
114 case. This is recommended for delivery via UUCP.
115 q Quote white space and other special characters in the
117 command-line $sender, $original_recipient and $recipient
118 address localparts (text to the left of the right-most @
119 character), according to an 8-bit transparent version of
120 RFC 822. This is recommended for delivery via UUCP or
121 BSMTP.
122 The result is compatible with the address parsing of com‐
124 mand-line recipients by the Postfix sendmail(1) mail sub‐
125 mission command.
126 The q flag affects only entire addresses, not the partial
128 address information from the $user, $extension or $mail‐
129 box command-line macros.
130 u Fold the command-line $original_recipient and $recipient
132 address localpart (text to the left of the right-most @
133 character) to lower case. This is recommended for deliv‐
134 ery via UUCP.
135 . Prepend "." to lines starting with ".". This is needed
137 by, for example, BSMTP software.
138 > Prepend ">" to lines starting with "From ". This is ex‐
140 pected by, for example, UUCP software.
141 null_sender=replacement (default: MAILER-DAEMON)
143 Replace the null sender address (typically used for delivery
144 status notifications) with the specified text when expanding the
145 $sender command-line macro, and when generating a From_ or Re‐
146 turn-Path: message header.
147 If the null sender replacement text is a non-empty string then
149 it is affected by the q flag for address quoting in command-line
150 arguments.
151 The null sender replacement text may be empty; this form is rec‐
153 ommended for content filters that feed mail back into Postfix.
154 The empty sender address is not affected by the q flag for ad‐
155 dress quoting in command-line arguments.
156 Caution: a null sender address is easily mis-parsed by naive
158 software. For example, when the pipe(8) daemon executes a com‐
159 mand such as:
160 Wrong: command -f$sender -- $recipient
162 the command will mis-parse the -f option value when the sender
164 address is a null string. For correct parsing, specify $sender
165 as an argument by itself:
166 Right: command -f $sender -- $recipient
168 NOTE: DO NOT put quotes around the command, $sender, or $recipi‐
169 ent.
170 This feature is available as of Postfix 2.3.
172 size=size_limit (optional)
174 Don't deliver messages that exceed this size limit (in bytes);
175 return them to the sender instead.
176 user=username (required)
178 user=username:groupname
180 Execute the external command with the user ID and group ID of
181 the specified username. The software refuses to execute com‐
182 mands with root privileges, or with the privileges of the mail
183 system owner. If groupname is specified, the corresponding group
184 ID is used instead of the group ID of username.
185 argv=command... (required)
187 The command to be executed. This must be specified as the last
188 command attribute. The command is executed directly, i.e. with‐
189 out interpretation of shell meta characters by a shell command
190 interpreter.
191 Specify "{" and "}" around command arguments that contain white‐
193 space (Postfix 3.0 and later). Whitespace after the opening "{"
194 and before the closing "}" is ignored.
195 In the command argument vector, the following macros are recog‐
197 nized and replaced with corresponding information from the Post‐
198 fix queue manager delivery request.
199 In addition to the form ${name}, the forms $name and the depre‐
201 cated form $(name) are also recognized. Specify $$ where a sin‐
202 gle $ is wanted.
203 ${client_address}
205 This macro expands to the remote client network address.
206 This feature is available as of Postfix 2.2.
208 ${client_helo}
210 This macro expands to the remote client HELO command pa‐
211 rameter.
212 This feature is available as of Postfix 2.2.
214 ${client_hostname}
216 This macro expands to the remote client hostname.
217 This feature is available as of Postfix 2.2.
219 ${client_port}
221 This macro expands to the remote client TCP port number.
222 This feature is available as of Postfix 2.5.
224 ${client_protocol}
226 This macro expands to the remote client protocol.
227 This feature is available as of Postfix 2.2.
229 ${domain}
231 This macro expands to the domain portion of the recipient
232 address. For example, with an address user+foo@domain
233 the domain is domain.
234 This information is modified by the h flag for case fold‐
236 ing.
237 This feature is available as of Postfix 2.5.
239 ${extension}
241 This macro expands to the extension part of a recipient
242 address. For example, with an address user+foo@domain
243 the extension is foo.
244 A command-line argument that contains ${extension} ex‐
246 pands into as many command-line arguments as there are
247 recipients.
248 This information is modified by the u flag for case fold‐
250 ing.
251 ${mailbox}
253 This macro expands to the complete local part of a recip‐
254 ient address. For example, with an address user+foo@do‐
255 main the mailbox is user+foo.
256 A command-line argument that contains ${mailbox} expands
258 to as many command-line arguments as there are recipi‐
259 ents.
260 This information is modified by the u flag for case fold‐
262 ing.
263 ${nexthop}
265 This macro expands to the next-hop hostname.
266 This information is modified by the h flag for case fold‐
268 ing.
269 ${original_recipient}
271 This macro expands to the complete recipient address be‐
272 fore any address rewriting or aliasing.
273 A command-line argument that contains ${original_recipi‐
275 ent} expands to as many command-line arguments as there
276 are recipients.
277 This information is modified by the hqu flags for quoting
279 and case folding.
280 This feature is available as of Postfix 2.5.
282 ${queue_id}
284 This macro expands to the queue id.
285 This feature is available as of Postfix 2.11.
287 ${recipient}
289 This macro expands to the complete recipient address.
290 A command-line argument that contains ${recipient} ex‐
292 pands to as many command-line arguments as there are re‐
293 cipients.
294 This information is modified by the hqu flags for quoting
296 and case folding.
297 ${sasl_method}
299 This macro expands to the name of the SASL authentication
300 mechanism in the AUTH command when the Postfix SMTP
301 server received the message.
302 This feature is available as of Postfix 2.2.
304 ${sasl_sender}
306 This macro expands to the SASL sender name (i.e. the
307 original submitter as per RFC 4954) in the MAIL FROM com‐
308 mand when the Postfix SMTP server received the message.
309 This feature is available as of Postfix 2.2.
311 ${sasl_username}
313 This macro expands to the SASL user name in the AUTH com‐
314 mand when the Postfix SMTP server received the message.
315 This feature is available as of Postfix 2.2.
317 ${sender}
319 This macro expands to the envelope sender address. By de‐
320 fault, the null sender address expands to MAILER-DAEMON;
321 this can be changed with the null_sender attribute, as
322 described above.
323 This information is modified by the q flag for quoting.
325 ${size}
327 This macro expands to Postfix's idea of the message size,
328 which is an approximation of the size of the message as
329 delivered.
330 ${user}
332 This macro expands to the username part of a recipient
333 address. For example, with an address user+foo@domain
334 the username part is user.
335 A command-line argument that contains ${user} expands
337 into as many command-line arguments as there are recipi‐
338 ents.
339 This information is modified by the u flag for case fold‐
341 ing.
342
344 RFC 3463 (Enhanced status codes)
345
347 Command exit status codes are expected to follow the conventions de‐
348 fined in <sysexits.h>. Exit status 0 means normal successful comple‐
349 tion.
350 In the case of a non-zero exit status, a limited amount of command out‐
352 put is logged, and reported in a delivery status notification. When
353 the output begins with a 4.X.X or 5.X.X enhanced status code, the sta‐
354 tus code takes precedence over the non-zero exit status (Postfix ver‐
355 sion 2.3 and later).
356 After successful delivery (zero exit status) a limited amount of com‐
358 mand output is logged, and reported in "success" delivery status noti‐
359 fications (Postfix 3.0 and later). This command output is not examined
360 for the presence of an enhanced status code.
361 Problems and transactions are logged to syslogd(8) or postlogd(8).
363 Corrupted message files are marked so that the queue manager can move
364 them to the corrupt queue for further inspection.
365
367 This program needs a dual personality 1) to access the private Postfix
368 queue and IPC mechanisms, and 2) to execute external commands as the
369 specified user. It is therefore security sensitive.
370
372 Changes to main.cf are picked up automatically as pipe(8) processes run
373 for only a limited amount of time. Use the command "postfix reload" to
374 speed up a change.
375 The text below provides only a parameter summary. See postconf(5) for
377 more details including examples.
378
380 In the text below, transport is the first field in a master.cf entry.
381 transport_time_limit ($command_time_limit)
383 A transport-specific override for the command_time_limit parame‐
384 ter value, where transport is the master.cf name of the message
385 delivery transport.
386 Implemented in the qmgr(8) daemon:
388 transport_destination_concurrency_limit ($default_destination_concur‐
390 rency_limit)
391 A transport-specific override for the default_destination_con‐
392 currency_limit parameter value, where transport is the master.cf
393 name of the message delivery transport.
394 transport_destination_recipient_limit ($default_destination_recipi‐
396 ent_limit)
397 A transport-specific override for the default_destination_recip‐
398 ient_limit parameter value, where transport is the master.cf
399 name of the message delivery transport.
400
402 config_directory (see 'postconf -d' output)
403 The default location of the Postfix main.cf and master.cf con‐
404 figuration files.
405 daemon_timeout (18000s)
407 How much time a Postfix daemon process may take to handle a re‐
408 quest before it is terminated by a built-in watchdog timer.
409 delay_logging_resolution_limit (2)
411 The maximal number of digits after the decimal point when log‐
412 ging sub-second delay values.
413 export_environment (see 'postconf -d' output)
415 The list of environment variables that a Postfix process will
416 export to non-Postfix processes.
417 ipc_timeout (3600s)
419 The time limit for sending or receiving information over an in‐
420 ternal communication channel.
421 mail_owner (postfix)
423 The UNIX system account that owns the Postfix queue and most
424 Postfix daemon processes.
425 max_idle (100s)
427 The maximum amount of time that an idle Postfix daemon process
428 waits for an incoming connection before terminating voluntarily.
429 max_use (100)
431 The maximal number of incoming connections that a Postfix daemon
432 process will service before terminating voluntarily.
433 process_id (read-only)
435 The process ID of a Postfix command or daemon process.
436 process_name (read-only)
438 The process name of a Postfix command or daemon process.
439 queue_directory (see 'postconf -d' output)
441 The location of the Postfix top-level queue directory.
442 recipient_delimiter (empty)
444 The set of characters that can separate an email address local‐
445 part, user name, or a .forward file name from its extension.
446 syslog_facility (mail)
448 The syslog facility of Postfix logging.
449 syslog_name (see 'postconf -d' output)
451 A prefix that is prepended to the process name in syslog
452 records, so that, for example, "smtpd" becomes "prefix/smtpd".
453 Available in Postfix version 3.0 and later:
455 pipe_delivery_status_filter ($default_delivery_status_filter)
457 Optional filter for the pipe(8) delivery agent to change the de‐
458 livery status code or explanatory text of successful or unsuc‐
459 cessful deliveries.
460 Available in Postfix version 3.3 and later:
462 enable_original_recipient (yes)
464 Enable support for the original recipient address after an ad‐
465 dress is rewritten to a different address (for example with
466 aliasing or with canonical mapping).
467 service_name (read-only)
469 The master.cf service name of a Postfix daemon process.
470 Available in Postfix 3.5 and later:
472 info_log_address_format (external)
474 The email address form that will be used in non-debug logging
475 (info, warning, etc.).
476
478 qmgr(8), queue manager
479 bounce(8), delivery status reports
480 postconf(5), configuration parameters
481 master(5), generic daemon options
482 master(8), process manager
483 postlogd(8), Postfix logging
484 syslogd(8), system logging
485
487 The Secure Mailer license must be distributed with this software.
488
490 Wietse Venema
491 IBM T.J. Watson Research
492 P.O. Box 704
493 Yorktown Heights, NY 10598, USA
494 Wietse Venema
496 Google, Inc.
497 111 8th Avenue
498 New York, NY 10011, USA
499 PIPE(8)