1SMTP(8) System Manager's Manual SMTP(8)
2
6 smtp - Postfix SMTP+LMTP client
7
9 smtp [generic Postfix daemon options]
10
12 The Postfix SMTP+LMTP client implements the SMTP and LMTP mail delivery
13 protocols. It processes message delivery requests from the queue man‐
14 ager. Each request specifies a queue file, a sender address, a domain
15 or host to deliver to, and recipient information. This program expects
16 to be run from the master(8) process manager.
17 The SMTP+LMTP client updates the queue file and marks recipients as
19 finished, or it informs the queue manager that delivery should be tried
20 again at a later time. Delivery status reports are sent to the
21 bounce(8), defer(8) or trace(8) daemon as appropriate.
22 The SMTP+LMTP client looks up a list of mail exchanger addresses for
24 the destination host, sorts the list by preference, and connects to
25 each listed address until it finds a server that responds.
26 When a server is not reachable, or when mail delivery fails due to a
28 recoverable error condition, the SMTP+LMTP client will try to deliver
29 the mail to an alternate host.
30 After a successful mail transaction, a connection may be saved to the
32 scache(8) connection cache server, so that it may be used by any
33 SMTP+LMTP client for a subsequent transaction.
34 By default, connection caching is enabled temporarily for destinations
36 that have a high volume of mail in the active queue. Connection caching
37 can be enabled permanently for specific destinations.
38
40 SMTP destinations have the following form:
41 domainname
43 domainname:port
45 Look up the mail exchangers for the specified domain, and con‐
46 nect to the specified port (default: smtp).
47 [hostname]
49 [hostname]:port
51 Look up the address(es) of the specified host, and connect to
52 the specified port (default: smtp).
53 [address]
55 [address]:port
57 Connect to the host at the specified address, and connect to the
58 specified port (default: smtp). An IPv6 address must be format‐
59 ted as [ipv6:address].
60
62 LMTP destinations have the following form:
63 unix:pathname
65 Connect to the local UNIX-domain server that is bound to the
66 specified pathname. If the process runs chrooted, an absolute
67 pathname is interpreted relative to the Postfix queue directory.
68 inet:hostname
70 inet:hostname:port
72 inet:[address]
74 inet:[address]:port
76 Connect to the specified TCP port on the specified local or
77 remote host. If no port is specified, connect to the port
78 defined as lmtp in services(4). If no such service is found,
79 the lmtp_tcp_port configuration parameter (default value of 24)
80 will be used. An IPv6 address must be formatted as
81 [ipv6:address].
82
84 The SMTP+LMTP client is moderately security-sensitive. It talks to SMTP
85 or LMTP servers and to DNS servers on the network. The SMTP+LMTP client
86 can be run chrooted at fixed low privilege.
87
89 RFC 821 (SMTP protocol)
90 RFC 822 (ARPA Internet Text Messages)
91 RFC 1651 (SMTP service extensions)
92 RFC 1652 (8bit-MIME transport)
93 RFC 1870 (Message Size Declaration)
94 RFC 2033 (LMTP protocol)
95 RFC 2034 (SMTP Enhanced Error Codes)
96 RFC 2045 (MIME: Format of Internet Message Bodies)
97 RFC 2046 (MIME: Media Types)
98 RFC 2554 (AUTH command)
99 RFC 2821 (SMTP protocol)
100 RFC 2920 (SMTP Pipelining)
101 RFC 3207 (STARTTLS command)
102 RFC 3461 (SMTP DSN Extension)
103 RFC 3463 (Enhanced Status Codes)
104 RFC 4954 (AUTH command)
105 RFC 5321 (SMTP protocol)
106
108 Problems and transactions are logged to syslogd(8). Corrupted message
109 files are marked so that the queue manager can move them to the corrupt
110 queue for further inspection.
111 Depending on the setting of the notify_classes parameter, the postmas‐
113 ter is notified of bounces, protocol problems, and of other trouble.
114
116 SMTP and LMTP connection caching does not work with TLS. The necessary
117 support for TLS object passivation and re-activation does not exist
118 without closing the session, which defeats the purpose.
119 SMTP and LMTP connection caching assumes that SASL credentials are
121 valid for all destinations that map onto the same IP address and TCP
122 port.
123
125 Before Postfix version 2.3, the LMTP client is a separate program that
126 implements only a subset of the functionality available with SMTP:
127 there is no support for TLS, and connections are cached in-process,
128 making it ineffective when the client is used for multiple domains.
129 Most smtp_xxx configuration parameters have an lmtp_xxx "mirror" param‐
131 eter for the equivalent LMTP feature. This document describes only
132 those LMTP-related parameters that aren't simply "mirror" parameters.
133 Changes to main.cf are picked up automatically, as smtp(8) processes
135 run for only a limited amount of time. Use the command "postfix reload"
136 to speed up a change.
137 The text below provides only a parameter summary. See postconf(5) for
139 more details including examples.
140
142 ignore_mx_lookup_error (no)
143 Ignore DNS MX lookups that produce no response.
144 smtp_always_send_ehlo (yes)
146 Always send EHLO at the start of an SMTP session.
147 smtp_never_send_ehlo (no)
149 Never send EHLO at the start of an SMTP session.
150 smtp_defer_if_no_mx_address_found (no)
152 Defer mail delivery when no MX record resolves to an IP address.
153 smtp_line_length_limit (998)
155 The maximal length of message header and body lines that Postfix
156 will send via SMTP.
157 smtp_pix_workaround_delay_time (10s)
159 How long the Postfix SMTP client pauses before sending
160 ".<CR><LF>" in order to work around the PIX firewall
161 "<CR><LF>.<CR><LF>" bug.
162 smtp_pix_workaround_threshold_time (500s)
164 How long a message must be queued before the Postfix SMTP client
165 turns on the PIX firewall "<CR><LF>.<CR><LF>" bug workaround for
166 delivery through firewalls with "smtp fixup" mode turned on.
167 smtp_pix_workarounds (disable_esmtp, delay_dotcrlf)
169 A list that specifies zero or more workarounds for CISCO PIX
170 firewall bugs.
171 smtp_pix_workaround_maps (empty)
173 Lookup tables, indexed by the remote SMTP server address, with
174 per-destination workarounds for CISCO PIX firewall bugs.
175 smtp_quote_rfc821_envelope (yes)
177 Quote addresses in Postfix SMTP client MAIL FROM and RCPT TO
178 commands as required by RFC 5321.
179 smtp_reply_filter (empty)
181 A mechanism to transform replies from remote SMTP servers one
182 line at a time.
183 smtp_skip_5xx_greeting (yes)
185 Skip remote SMTP servers that greet with a 5XX status code (go
186 away, do not try again later).
187 smtp_skip_quit_response (yes)
189 Do not wait for the response to the SMTP QUIT command.
190 Available in Postfix version 2.0 and earlier:
192 smtp_skip_4xx_greeting (yes)
194 Skip SMTP servers that greet with a 4XX status code (go away,
195 try again later).
196 Available in Postfix version 2.2 and later:
198 smtp_discard_ehlo_keyword_address_maps (empty)
200 Lookup tables, indexed by the remote SMTP server address, with
201 case insensitive lists of EHLO keywords (pipelining, starttls,
202 auth, etc.) that the Postfix SMTP client will ignore in the EHLO
203 response from a remote SMTP server.
204 smtp_discard_ehlo_keywords (empty)
206 A case insensitive list of EHLO keywords (pipelining, starttls,
207 auth, etc.) that the Postfix SMTP client will ignore in the EHLO
208 response from a remote SMTP server.
209 smtp_generic_maps (empty)
211 Optional lookup tables that perform address rewriting in the
212 Postfix SMTP client, typically to transform a locally valid
213 address into a globally valid address when sending mail across
214 the Internet.
215 Available in Postfix version 2.2.9 and later:
217 smtp_cname_overrides_servername (version dependent)
219 Allow DNS CNAME records to override the servername that the
220 Postfix SMTP client uses for logging, SASL password lookup, TLS
221 policy decisions, or TLS certificate verification.
222 Available in Postfix version 2.3 and later:
224 lmtp_discard_lhlo_keyword_address_maps (empty)
226 Lookup tables, indexed by the remote LMTP server address, with
227 case insensitive lists of LHLO keywords (pipelining, starttls,
228 auth, etc.) that the Postfix LMTP client will ignore in the LHLO
229 response from a remote LMTP server.
230 lmtp_discard_lhlo_keywords (empty)
232 A case insensitive list of LHLO keywords (pipelining, starttls,
233 auth, etc.) that the Postfix LMTP client will ignore in the LHLO
234 response from a remote LMTP server.
235 Available in Postfix version 2.4.4 and later:
237 send_cyrus_sasl_authzid (no)
239 When authenticating to a remote SMTP or LMTP server with the
240 default setting "no", send no SASL authoriZation ID (authzid);
241 send only the SASL authentiCation ID (authcid) plus the auth‐
242 cid's password.
243 Available in Postfix version 2.5 and later:
245 smtp_header_checks (empty)
247 Restricted header_checks(5) tables for the Postfix SMTP client.
248 smtp_mime_header_checks (empty)
250 Restricted mime_header_checks(5) tables for the Postfix SMTP
251 client.
252 smtp_nested_header_checks (empty)
254 Restricted nested_header_checks(5) tables for the Postfix SMTP
255 client.
256 smtp_body_checks (empty)
258 Restricted body_checks(5) tables for the Postfix SMTP client.
259 Available in Postfix version 2.6 and later:
261 tcp_windowsize (0)
263 An optional workaround for routers that break TCP window scal‐
264 ing.
265 Available in Postfix version 2.8 and later:
267 smtp_dns_resolver_options (empty)
269 DNS Resolver options for the Postfix SMTP client.
270 Available in Postfix version 2.9 and later:
272 smtp_per_record_deadline (no)
274 Change the behavior of the smtp_*_timeout time limits, from a
275 time limit per read or write system call, to a time limit to
276 send or receive a complete record (an SMTP command line, SMTP
277 response line, SMTP message content line, or TLS protocol mes‐
278 sage).
279 smtp_send_dummy_mail_auth (no)
281 Whether or not to append the "AUTH=<>" option to the MAIL FROM
282 command in SASL-authenticated SMTP sessions.
283
285 Available in Postfix version 2.0 and later:
286 disable_mime_output_conversion (no)
288 Disable the conversion of 8BITMIME format to 7BIT format.
289 mime_boundary_length_limit (2048)
291 The maximal length of MIME multipart boundary strings.
292 mime_nesting_limit (100)
294 The maximal recursion level that the MIME processor will handle.
295
297 Available in Postfix version 2.1 and later:
298 smtp_send_xforward_command (no)
300 Send the non-standard XFORWARD command when the Postfix SMTP
301 server EHLO response announces XFORWARD support.
302
304 smtp_sasl_auth_enable (no)
305 Enable SASL authentication in the Postfix SMTP client.
306 smtp_sasl_password_maps (empty)
308 Optional Postfix SMTP client lookup tables with one user‐
309 name:password entry per remote hostname or domain, or sender
310 address when sender-dependent authentication is enabled.
311 smtp_sasl_security_options (noplaintext, noanonymous)
313 Postfix SMTP client SASL security options; as of Postfix 2.3 the
314 list of available features depends on the SASL client implemen‐
315 tation that is selected with smtp_sasl_type.
316 Available in Postfix version 2.2 and later:
318 smtp_sasl_mechanism_filter (empty)
320 If non-empty, a Postfix SMTP client filter for the remote SMTP
321 server's list of offered SASL mechanisms.
322 Available in Postfix version 2.3 and later:
324 smtp_sender_dependent_authentication (no)
326 Enable sender-dependent authentication in the Postfix SMTP
327 client; this is available only with SASL authentication, and
328 disables SMTP connection caching to ensure that mail from dif‐
329 ferent senders will use the appropriate credentials.
330 smtp_sasl_path (empty)
332 Implementation-specific information that the Postfix SMTP client
333 passes through to the SASL plug-in implementation that is
334 selected with smtp_sasl_type.
335 smtp_sasl_type (cyrus)
337 The SASL plug-in type that the Postfix SMTP client should use
338 for authentication.
339 Available in Postfix version 2.5 and later:
341 smtp_sasl_auth_cache_name (empty)
343 An optional table to prevent repeated SASL authentication fail‐
344 ures with the same remote SMTP server hostname, username and
345 password.
346 smtp_sasl_auth_cache_time (90d)
348 The maximal age of an smtp_sasl_auth_cache_name entry before it
349 is removed.
350 smtp_sasl_auth_soft_bounce (yes)
352 When a remote SMTP server rejects a SASL authentication request
353 with a 535 reply code, defer mail delivery instead of returning
354 mail as undeliverable.
355 Available in Postfix version 2.9 and later:
357 smtp_send_dummy_mail_auth (no)
359 Whether or not to append the "AUTH=<>" option to the MAIL FROM
360 command in SASL-authenticated SMTP sessions.
361
363 Detailed information about STARTTLS configuration may be found in the
364 TLS_README document.
365 smtp_tls_security_level (empty)
367 The default SMTP TLS security level for the Postfix SMTP client;
368 when a non-empty value is specified, this overrides the obsolete
369 parameters smtp_use_tls, smtp_enforce_tls, and
370 smtp_tls_enforce_peername.
371 smtp_sasl_tls_security_options ($smtp_sasl_security_options)
373 The SASL authentication security options that the Postfix SMTP
374 client uses for TLS encrypted SMTP sessions.
375 smtp_starttls_timeout (300s)
377 Time limit for Postfix SMTP client write and read operations
378 during TLS startup and shutdown handshake procedures.
379 smtp_tls_CAfile (empty)
381 A file containing CA certificates of root CAs trusted to sign
382 either remote SMTP server certificates or intermediate CA cer‐
383 tificates.
384 smtp_tls_CApath (empty)
386 Directory with PEM format certificate authority certificates
387 that the Postfix SMTP client uses to verify a remote SMTP server
388 certificate.
389 smtp_tls_cert_file (empty)
391 File with the Postfix SMTP client RSA certificate in PEM format.
392 smtp_tls_mandatory_ciphers (medium)
394 The minimum TLS cipher grade that the Postfix SMTP client will
395 use with mandatory TLS encryption.
396 smtp_tls_exclude_ciphers (empty)
398 List of ciphers or cipher types to exclude from the Postfix SMTP
399 client cipher list at all TLS security levels.
400 smtp_tls_mandatory_exclude_ciphers (empty)
402 Additional list of ciphers or cipher types to exclude from the
403 Postfix SMTP client cipher list at mandatory TLS security lev‐
404 els.
405 smtp_tls_dcert_file (empty)
407 File with the Postfix SMTP client DSA certificate in PEM format.
408 smtp_tls_dkey_file ($smtp_tls_dcert_file)
410 File with the Postfix SMTP client DSA private key in PEM format.
411 smtp_tls_key_file ($smtp_tls_cert_file)
413 File with the Postfix SMTP client RSA private key in PEM format.
414 smtp_tls_loglevel (0)
416 Enable additional Postfix SMTP client logging of TLS activity.
417 smtp_tls_note_starttls_offer (no)
419 Log the hostname of a remote SMTP server that offers STARTTLS,
420 when TLS is not already enabled for that server.
421 smtp_tls_policy_maps (empty)
423 Optional lookup tables with the Postfix SMTP client TLS security
424 policy by next-hop destination; when a non-empty value is speci‐
425 fied, this overrides the obsolete smtp_tls_per_site parameter.
426 smtp_tls_mandatory_protocols (!SSLv2)
428 List of SSL/TLS protocols that the Postfix SMTP client will use
429 with mandatory TLS encryption.
430 smtp_tls_scert_verifydepth (9)
432 The verification depth for remote SMTP server certificates.
433 smtp_tls_secure_cert_match (nexthop, dot-nexthop)
435 How the Postfix SMTP client verifies the server certificate
436 peername for the "secure" TLS security level.
437 smtp_tls_session_cache_database (empty)
439 Name of the file containing the optional Postfix SMTP client TLS
440 session cache.
441 smtp_tls_session_cache_timeout (3600s)
443 The expiration time of Postfix SMTP client TLS session cache
444 information.
445 smtp_tls_verify_cert_match (hostname)
447 How the Postfix SMTP client verifies the server certificate
448 peername for the "verify" TLS security level.
449 tls_daemon_random_bytes (32)
451 The number of pseudo-random bytes that an smtp(8) or smtpd(8)
452 process requests from the tlsmgr(8) server in order to seed its
453 internal pseudo random number generator (PRNG).
454 tls_high_cipherlist (ALL:!EXPORT:!LOW:!MEDIUM:+RC4:@STRENGTH)
456 The OpenSSL cipherlist for "HIGH" grade ciphers.
457 tls_medium_cipherlist (ALL:!EXPORT:!LOW:+RC4:@STRENGTH)
459 The OpenSSL cipherlist for "MEDIUM" or higher grade ciphers.
460 tls_low_cipherlist (ALL:!EXPORT:+RC4:@STRENGTH)
462 The OpenSSL cipherlist for "LOW" or higher grade ciphers.
463 tls_export_cipherlist (ALL:+RC4:@STRENGTH)
465 The OpenSSL cipherlist for "EXPORT" or higher grade ciphers.
466 tls_null_cipherlist (eNULL:!aNULL)
468 The OpenSSL cipherlist for "NULL" grade ciphers that provide
469 authentication without encryption.
470 Available in Postfix version 2.4 and later:
472 smtp_sasl_tls_verified_security_options ($smtp_sasl_tls_secu‐
474 rity_options)
475 The SASL authentication security options that the Postfix SMTP
476 client uses for TLS encrypted SMTP sessions with a verified
477 server certificate.
478 Available in Postfix version 2.5 and later:
480 smtp_tls_fingerprint_cert_match (empty)
482 List of acceptable remote SMTP server certificate fingerprints
483 for the "fingerprint" TLS security level (smtp_tls_secu‐
484 rity_level = fingerprint).
485 smtp_tls_fingerprint_digest (md5)
487 The message digest algorithm used to construct remote SMTP
488 server certificate fingerprints.
489 Available in Postfix version 2.6 and later:
491 smtp_tls_protocols (!SSLv2)
493 List of TLS protocols that the Postfix SMTP client will exclude
494 or include with opportunistic TLS encryption.
495 smtp_tls_ciphers (export)
497 The minimum TLS cipher grade that the Postfix SMTP client will
498 use with opportunistic TLS encryption.
499 smtp_tls_eccert_file (empty)
501 File with the Postfix SMTP client ECDSA certificate in PEM for‐
502 mat.
503 smtp_tls_eckey_file ($smtp_tls_eccert_file)
505 File with the Postfix SMTP client ECDSA private key in PEM for‐
506 mat.
507 Available in Postfix version 2.7 and later:
509 smtp_tls_block_early_mail_reply (no)
511 Try to detect a mail hijacking attack based on a TLS protocol
512 vulnerability (CVE-2009-3555), where an attacker prepends mali‐
513 cious HELO, MAIL, RCPT, DATA commands to a Postfix SMTP client
514 TLS session.
515 Available in Postfix version 2.8 and later:
517 tls_disable_workarounds (see 'postconf -d' output)
519 List or bit-mask of OpenSSL bug work-arounds to disable.
520
522 The following configuration parameters exist for compatibility with
523 Postfix versions before 2.3. Support for these will be removed in a
524 future release.
525 smtp_use_tls (no)
527 Opportunistic mode: use TLS when a remote SMTP server announces
528 STARTTLS support, otherwise send the mail in the clear.
529 smtp_enforce_tls (no)
531 Enforcement mode: require that remote SMTP servers use TLS
532 encryption, and never send mail in the clear.
533 smtp_tls_enforce_peername (yes)
535 With mandatory TLS encryption, require that the remote SMTP
536 server hostname matches the information in the remote SMTP
537 server certificate.
538 smtp_tls_per_site (empty)
540 Optional lookup tables with the Postfix SMTP client TLS usage
541 policy by next-hop destination and by remote SMTP server host‐
542 name.
543 smtp_tls_cipherlist (empty)
545 Obsolete Postfix < 2.3 control for the Postfix SMTP client TLS
546 cipher list.
547
549 smtp_destination_concurrency_limit ($default_destination_concur‐
550 rency_limit)
551 The maximal number of parallel deliveries to the same destina‐
552 tion via the smtp message delivery transport.
553 smtp_destination_recipient_limit ($default_destination_recipient_limit)
555 The maximal number of recipients per message for the smtp mes‐
556 sage delivery transport.
557 smtp_connect_timeout (30s)
559 The Postfix SMTP client time limit for completing a TCP connec‐
560 tion, or zero (use the operating system built-in time limit).
561 smtp_helo_timeout (300s)
563 The Postfix SMTP client time limit for sending the HELO or EHLO
564 command, and for receiving the initial remote SMTP server
565 response.
566 lmtp_lhlo_timeout (300s)
568 The Postfix LMTP client time limit for sending the LHLO command,
569 and for receiving the initial remote LMTP server response.
570 smtp_xforward_timeout (300s)
572 The Postfix SMTP client time limit for sending the XFORWARD com‐
573 mand, and for receiving the remote SMTP server response.
574 smtp_mail_timeout (300s)
576 The Postfix SMTP client time limit for sending the MAIL FROM
577 command, and for receiving the remote SMTP server response.
578 smtp_rcpt_timeout (300s)
580 The Postfix SMTP client time limit for sending the SMTP RCPT TO
581 command, and for receiving the remote SMTP server response.
582 smtp_data_init_timeout (120s)
584 The Postfix SMTP client time limit for sending the SMTP DATA
585 command, and for receiving the remote SMTP server response.
586 smtp_data_xfer_timeout (180s)
588 The Postfix SMTP client time limit for sending the SMTP message
589 content.
590 smtp_data_done_timeout (600s)
592 The Postfix SMTP client time limit for sending the SMTP ".", and
593 for receiving the remote SMTP server response.
594 smtp_quit_timeout (300s)
596 The Postfix SMTP client time limit for sending the QUIT command,
597 and for receiving the remote SMTP server response.
598 Available in Postfix version 2.1 and later:
600 smtp_mx_address_limit (5)
602 The maximal number of MX (mail exchanger) IP addresses that can
603 result from Postfix SMTP client mail exchanger lookups, or zero
604 (no limit).
605 smtp_mx_session_limit (2)
607 The maximal number of SMTP sessions per delivery request before
608 the Postfix SMTP client gives up or delivers to a fall-back
609 relay host, or zero (no limit).
610 smtp_rset_timeout (20s)
612 The Postfix SMTP client time limit for sending the RSET command,
613 and for receiving the remote SMTP server response.
614 Available in Postfix version 2.2 and earlier:
616 lmtp_cache_connection (yes)
618 Keep Postfix LMTP client connections open for up to $max_idle
619 seconds.
620 Available in Postfix version 2.2 and later:
622 smtp_connection_cache_destinations (empty)
624 Permanently enable SMTP connection caching for the specified
625 destinations.
626 smtp_connection_cache_on_demand (yes)
628 Temporarily enable SMTP connection caching while a destination
629 has a high volume of mail in the active queue.
630 smtp_connection_reuse_time_limit (300s)
632 The amount of time during which Postfix will use an SMTP connec‐
633 tion repeatedly.
634 smtp_connection_cache_time_limit (2s)
636 When SMTP connection caching is enabled, the amount of time that
637 an unused SMTP client socket is kept open before it is closed.
638 Available in Postfix version 2.3 and later:
640 connection_cache_protocol_timeout (5s)
642 Time limit for connection cache connect, send or receive opera‐
643 tions.
644 Available in Postfix version 2.9 and later:
646 smtp_per_record_deadline (no)
648 Change the behavior of the smtp_*_timeout time limits, from a
649 time limit per read or write system call, to a time limit to
650 send or receive a complete record (an SMTP command line, SMTP
651 response line, SMTP message content line, or TLS protocol mes‐
652 sage).
653
655 debug_peer_level (2)
656 The increment in verbose logging level when a remote client or
657 server matches a pattern in the debug_peer_list parameter.
658 debug_peer_list (empty)
660 Optional list of remote client or server hostname or network
661 address patterns that cause the verbose logging level to
662 increase by the amount specified in $debug_peer_level.
663 error_notice_recipient (postmaster)
665 The recipient of postmaster notifications about mail delivery
666 problems that are caused by policy, resource, software or proto‐
667 col errors.
668 internal_mail_filter_classes (empty)
670 What categories of Postfix-generated mail are subject to before-
671 queue content inspection by non_smtpd_milters, header_checks and
672 body_checks.
673 notify_classes (resource, software)
675 The list of error classes that are reported to the postmaster.
676
678 best_mx_transport (empty)
679 Where the Postfix SMTP client should deliver mail when it
680 detects a "mail loops back to myself" error condition.
681 config_directory (see 'postconf -d' output)
683 The default location of the Postfix main.cf and master.cf con‐
684 figuration files.
685 daemon_timeout (18000s)
687 How much time a Postfix daemon process may take to handle a
688 request before it is terminated by a built-in watchdog timer.
689 delay_logging_resolution_limit (2)
691 The maximal number of digits after the decimal point when log‐
692 ging sub-second delay values.
693 disable_dns_lookups (no)
695 Disable DNS lookups in the Postfix SMTP and LMTP clients.
696 inet_interfaces (all)
698 The network interface addresses that this mail system receives
699 mail on.
700 inet_protocols (all)
702 The Internet protocols Postfix will attempt to use when making
703 or accepting connections.
704 ipc_timeout (3600s)
706 The time limit for sending or receiving information over an
707 internal communication channel.
708 lmtp_assume_final (no)
710 When a remote LMTP server announces no DSN support, assume that
711 the server performs final delivery, and send "delivered" deliv‐
712 ery status notifications instead of "relayed".
713 lmtp_tcp_port (24)
715 The default TCP port that the Postfix LMTP client connects to.
716 max_idle (100s)
718 The maximum amount of time that an idle Postfix daemon process
719 waits for an incoming connection before terminating voluntarily.
720 max_use (100)
722 The maximal number of incoming connections that a Postfix daemon
723 process will service before terminating voluntarily.
724 process_id (read-only)
726 The process ID of a Postfix command or daemon process.
727 process_name (read-only)
729 The process name of a Postfix command or daemon process.
730 proxy_interfaces (empty)
732 The network interface addresses that this mail system receives
733 mail on by way of a proxy or network address translation unit.
734 smtp_address_preference (any)
736 The address type ("ipv6", "ipv4" or "any") that the Postfix SMTP
737 client will try first, when a destination has IPv6 and IPv4
738 addresses with equal MX preference.
739 smtp_bind_address (empty)
741 An optional numerical network address that the Postfix SMTP
742 client should bind to when making an IPv4 connection.
743 smtp_bind_address6 (empty)
745 An optional numerical network address that the Postfix SMTP
746 client should bind to when making an IPv6 connection.
747 smtp_helo_name ($myhostname)
749 The hostname to send in the SMTP EHLO or HELO command.
750 lmtp_lhlo_name ($myhostname)
752 The hostname to send in the LMTP LHLO command.
753 smtp_host_lookup (dns)
755 What mechanisms the Postfix SMTP client uses to look up a host's
756 IP address.
757 smtp_randomize_addresses (yes)
759 Randomize the order of equal-preference MX host addresses.
760 syslog_facility (mail)
762 The syslog facility of Postfix logging.
763 syslog_name (see 'postconf -d' output)
765 The mail system name that is prepended to the process name in
766 syslog records, so that "smtpd" becomes, for example, "post‐
767 fix/smtpd".
768 Available with Postfix 2.2 and earlier:
770 fallback_relay (empty)
772 Optional list of relay hosts for SMTP destinations that can't be
773 found or that are unreachable.
774 Available with Postfix 2.3 and later:
776 smtp_fallback_relay ($fallback_relay)
778 Optional list of relay hosts for SMTP destinations that can't be
779 found or that are unreachable.
780
782 generic(5), output address rewriting
783 header_checks(5), message header content inspection
784 body_checks(5), body parts content inspection
785 qmgr(8), queue manager
786 bounce(8), delivery status reports
787 scache(8), connection cache server
788 postconf(5), configuration parameters
789 master(5), generic daemon options
790 master(8), process manager
791 tlsmgr(8), TLS session and PRNG management
792 syslogd(8), system logging
793
795 Use "postconf readme_directory" or "postconf html_directory" to locate
796 this information.
797 SASL_README, Postfix SASL howto
798 TLS_README, Postfix STARTTLS howto
799
801 The Secure Mailer license must be distributed with this software.
802
804 Wietse Venema
805 IBM T.J. Watson Research
806 P.O. Box 704
807 Yorktown Heights, NY 10598, USA
808 Command pipelining in cooperation with:
810 Jon Ribbens
811 Oaktree Internet Solutions Ltd.,
812 Internet House,
813 Canal Basin,
814 Coventry,
815 CV1 4LY, United Kingdom.
816 SASL support originally by:
818 Till Franke
819 SuSE Rhein/Main AG
820 65760 Eschborn, Germany
821 TLS support originally by:
823 Lutz Jaenicke
824 BTU Cottbus
825 Allgemeine Elektrotechnik
826 Universitaetsplatz 3-4
827 D-03044 Cottbus, Germany
828 Revised TLS and SMTP connection cache support by:
830 Victor Duchovni
831 Morgan Stanley
832 SMTP(8)