1ACCESS(5) File Formats Manual ACCESS(5)
2
6 access - Postfix SMTP server access table
7
9 postmap /etc/postfix/access
10 postmap -q "string" /etc/postfix/access
12 postmap -q - /etc/postfix/access <inputfile
14
16 This document describes access control on remote SMTP client informa‐
17 tion: host names, network addresses, and envelope sender or recipient
18 addresses; it is implemented by the Postfix SMTP server. See
19 header_checks(5) or body_checks(5) for access control on the content of
20 email messages.
21 Normally, the access(5) table is specified as a text file that serves
23 as input to the postmap(1) command. The result, an indexed file in dbm
24 or db format, is used for fast searching by the mail system. Execute
25 the command "postmap /etc/postfix/access" to rebuild an indexed file
26 after changing the corresponding text file.
27 When the table is provided via other means such as NIS, LDAP or SQL,
29 the same lookups are done as for ordinary indexed files.
30 Alternatively, the table can be provided as a regular-expression map
32 where patterns are given as regular expressions, or lookups can be
33 directed to TCP-based server. In those cases, the lookups are done in a
34 slightly different way as described below under "REGULAR EXPRESSION
35 TABLES" or "TCP-BASED TABLES".
36
38 The search string is folded to lowercase before database lookup. As of
39 Postfix 2.3, the search string is not case folded with database types
40 such as regexp: or pcre: whose lookup fields can match both upper and
41 lower case.
42
44 The input format for the postmap(1) command is as follows:
45 pattern action
47 When pattern matches a mail address, domain or host address,
48 perform the corresponding action.
49 blank lines and comments
51 Empty lines and whitespace-only lines are ignored, as are lines
52 whose first non-whitespace character is a `#'.
53 multi-line text
55 A logical line starts with non-whitespace text. A line that
56 starts with whitespace continues a logical line.
57
59 With lookups from indexed files such as DB or DBM, or from networked
60 tables such as NIS, LDAP or SQL, patterns are tried in the order as
61 listed below:
62 user@domain
64 Matches the specified mail address.
65 domain.tld
67 Matches domain.tld as the domain part of an email address.
68 The pattern domain.tld also matches subdomains, but only when
70 the string smtpd_access_maps is listed in the Postfix par‐
71 ent_domain_matches_subdomains configuration setting.
72 .domain.tld
74 Matches subdomains of domain.tld, but only when the string
75 smtpd_access_maps is not listed in the Postfix par‐
76 ent_domain_matches_subdomains configuration setting.
77 user@ Matches all mail addresses with the specified user part.
79 Note: lookup of the null sender address is not possible with some types
81 of lookup table. By default, Postfix uses <> as the lookup key for such
82 addresses. The value is specified with the smtpd_null_access_lookup_key
83 parameter in the Postfix main.cf file.
84
86 When a mail address localpart contains the optional recipient delimiter
87 (e.g., user+foo@domain), the lookup order becomes: user+foo@domain,
88 user@domain, domain, user+foo@, and user@.
89
91 With lookups from indexed files such as DB or DBM, or from networked
92 tables such as NIS, LDAP or SQL, the following lookup patterns are
93 examined in the order as listed:
94 domain.tld
96 Matches domain.tld.
97 The pattern domain.tld also matches subdomains, but only when
99 the string smtpd_access_maps is listed in the Postfix par‐
100 ent_domain_matches_subdomains configuration setting.
101 .domain.tld
103 Matches subdomains of domain.tld, but only when the string
104 smtpd_access_maps is not listed in the Postfix par‐
105 ent_domain_matches_subdomains configuration setting.
106 net.work.addr.ess
108 net.work.addr
110 net.work
112 net Matches the specified IPv4 host address or subnetwork. An IPv4
114 host address is a sequence of four decimal octets separated by
115 ".".
116 Subnetworks are matched by repeatedly truncating the last
118 ".octet" from the remote IPv4 host address string until a match
119 is found in the access table, or until further truncation is not
120 possible.
121 NOTE 1: The access map lookup key must be in canonical form: do
123 not specify unnecessary null characters, and do not enclose net‐
124 work address information with "[]" characters.
125 NOTE 2: use the cidr lookup table type to specify network/net‐
127 mask patterns. See cidr_table(5) for details.
128 net:work:addr:ess
130 net:work:addr
132 net:work
134 net Matches the specified IPv6 host address or subnetwork. An IPv6
136 host address is a sequence of three to eight hexadecimal octet
137 pairs separated by ":".
138 Subnetworks are matched by repeatedly truncating the last
140 ":octetpair" from the remote IPv6 host address string until a
141 match is found in the access table, or until further truncation
142 is not possible.
143 NOTE 1: the truncation and comparison are done with the string
145 representation of the IPv6 host address. Thus, not all the ":"
146 subnetworks will be tried.
147 NOTE 2: The access map lookup key must be in canonical form: do
149 not specify unnecessary null characters, and do not enclose net‐
150 work address information with "[]" characters.
151 NOTE 3: use the cidr lookup table type to specify network/net‐
153 mask patterns. See cidr_table(5) for details.
154 IPv6 support is available in Postfix 2.2 and later.
156
158 OK Accept the address etc. that matches the pattern.
159 all-numerical
161 An all-numerical result is treated as OK. This format is gener‐
162 ated by address-based relay authorization schemes such as
163 pop-before-smtp.
164 For other accept actions, see "OTHER ACTIONS" below.
166
168 Postfix version 2.3 and later support enhanced status codes as defined
169 in RFC 3463. When no code is specified at the beginning of the text
170 below, Postfix inserts a default enhanced status code of "5.7.1" in the
171 case of reject actions, and "4.7.1" in the case of defer actions. See
172 "ENHANCED STATUS CODES" below.
173 4NN text
175 5NN text
177 Reject the address etc. that matches the pattern, and respond
178 with the numerical three-digit code and text. 4NN means "try
179 again later", while 5NN means "do not try again".
180 The following responses have special meaning for the Postfix
182 SMTP server:
183 421 text (Postfix 2.3 and later)
185 521 text (Postfix 2.6 and later)
187 After responding with the numerical three-digit code and
188 text, disconnect immediately from the SMTP client. This
189 frees up SMTP server resources so that they can be made
190 available to another SMTP client.
191 Note: The "521" response should be used only with botnets
193 and other malware where interoperability is of no con‐
194 cern. The "send 521 and disconnect" behavior is NOT
195 defined in the SMTP standard.
196 REJECT optional text...
198 Reject the address etc. that matches the pattern. Reply with
199 "$access_map_reject_code optional text..." when the optional
200 text is specified, otherwise reply with a generic error response
201 message.
202 DEFER optional text...
204 Reject the address etc. that matches the pattern. Reply with
205 "$access_map_defer_code optional text..." when the optional text
206 is specified, otherwise reply with a generic error response mes‐
207 sage.
208 This feature is available in Postfix 2.6 and later.
210 DEFER_IF_REJECT optional text...
212 Defer the request if some later restriction would result in a
213 REJECT action. Reply with "$access_map_defer_code 4.7.1 optional
214 text..." when the optional text is specified, otherwise reply
215 with a generic error response message.
216 Prior to Postfix 2.6, the SMTP reply code is 450.
218 This feature is available in Postfix 2.1 and later.
220 DEFER_IF_PERMIT optional text...
222 Defer the request if some later restriction would result in a an
223 explicit or implicit PERMIT action. Reply with
224 "$access_map_defer_code 4.7.1 optional text..." when the
225 optional text is specified, otherwise reply with a generic error
226 response message.
227 Prior to Postfix 2.6, the SMTP reply code is 450.
229 This feature is available in Postfix 2.1 and later.
231 For other reject actions, see "OTHER ACTIONS" below.
233
235 restriction...
236 Apply the named UCE restriction(s) (permit, reject,
237 reject_unauth_destination, and so on).
238 BCC user@domain
240 Send one copy of the message to the specified recipient.
241 If multiple BCC actions are specified within the same SMTP MAIL
243 transaction, with Postfix 3.0 only the last action will be used.
244 This feature is available in Postfix 3.0 and later.
246 DISCARD optional text...
248 Claim successful delivery and silently discard the message. Log
249 the optional text if specified, otherwise log a generic message.
250 Note: this action currently affects all recipients of the mes‐
252 sage. To discard only one recipient without discarding the
253 entire message, use the transport(5) table to direct mail to the
254 discard(8) service.
255 This feature is available in Postfix 2.0 and later.
257 DUNNO Pretend that the lookup key was not found. This prevents Postfix
259 from trying substrings of the lookup key (such as a subdomain
260 name, or a network address subnetwork).
261 This feature is available in Postfix 2.0 and later.
263 FILTER transport:destination
265 After the message is queued, send the entire message through the
266 specified external content filter. The transport name specifies
267 the first field of a mail delivery agent definition in mas‐
268 ter.cf; the syntax of the next-hop destination is described in
269 the manual page of the corresponding delivery agent. More
270 information about external content filters is in the Postfix
271 FILTER_README file.
272 Note 1: do not use $number regular expression substitutions for
274 transport or destination unless you know that the information
275 has a trusted origin.
276 Note 2: this action overrides the main.cf content_filter set‐
278 ting, and affects all recipients of the message. In the case
279 that multiple FILTER actions fire, only the last one is exe‐
280 cuted.
281 Note 3: the purpose of the FILTER command is to override message
283 routing. To override the recipient's transport but not the
284 next-hop destination, specify an empty filter destination (Post‐
285 fix 2.7 and later), or specify a transport:destination that
286 delivers through a different Postfix instance (Postfix 2.6 and
287 earlier). Other options are using the recipient-dependent trans‐
288 port_maps or the sender-dependent sender_dependent_default‐
289 _transport_maps features.
290 This feature is available in Postfix 2.0 and later.
292 HOLD optional text...
294 Place the message on the hold queue, where it will sit until
295 someone either deletes it or releases it for delivery. Log the
296 optional text if specified, otherwise log a generic message.
297 Mail that is placed on hold can be examined with the postcat(1)
299 command, and can be destroyed or released with the postsuper(1)
300 command.
301 Note: use "postsuper -r" to release mail that was kept on hold
303 for a significant fraction of $maximal_queue_lifetime or
304 $bounce_queue_lifetime, or longer. Use "postsuper -H" only for
305 mail that will not expire within a few delivery attempts.
306 Note: this action currently affects all recipients of the mes‐
308 sage.
309 This feature is available in Postfix 2.0 and later.
311 PREPEND headername: headervalue
313 Prepend the specified message header to the message. When more
314 than one PREPEND action executes, the first prepended header
315 appears before the second etc. prepended header.
316 Note: this action must execute before the message content is
318 received; it cannot execute in the context of
319 smtpd_end_of_data_restrictions.
320 This feature is available in Postfix 2.1 and later.
322 REDIRECT user@domain
324 After the message is queued, send the message to the specified
325 address instead of the intended recipient(s). When multiple RE‐
326 DIRECT actions fire, only the last one takes effect.
327 Note: this action overrides the FILTER action, and currently
329 overrides all recipients of the message.
330 This feature is available in Postfix 2.1 and later.
332 INFO optional text...
334 Log an informational record with the optional text, together
335 with client information and if available, with helo, sender,
336 recipient and protocol information.
337 This feature is available in Postfix 3.0 and later.
339 WARN optional text...
341 Log a warning with the optional text, together with client
342 information and if available, with helo, sender, recipient and
343 protocol information.
344 This feature is available in Postfix 2.1 and later.
346
348 Postfix version 2.3 and later support enhanced status codes as defined
349 in RFC 3463. When an enhanced status code is specified in an access
350 table, it is subject to modification. The following transformations are
351 needed when the same access table is used for client, helo, sender, or
352 recipient access restrictions; they happen regardless of whether Post‐
353 fix replies to a MAIL FROM, RCPT TO or other SMTP command.
354 · When a sender address matches a REJECT action, the Postfix SMTP
356 server will transform a recipient DSN status (e.g., 4.1.1-4.1.6)
357 into the corresponding sender DSN status, and vice versa.
358 · When non-address information matches a REJECT action (such as
360 the HELO command argument or the client hostname/address), the
361 Postfix SMTP server will transform a sender or recipient DSN
362 status into a generic non-address DSN status (e.g., 4.0.0).
363
365 This section describes how the table lookups change when the table is
366 given in the form of regular expressions. For a description of regular
367 expression lookup table syntax, see regexp_table(5) or pcre_table(5).
368 Each pattern is a regular expression that is applied to the entire
370 string being looked up. Depending on the application, that string is an
371 entire client hostname, an entire client IP address, or an entire mail
372 address. Thus, no parent domain or parent network search is done,
373 user@domain mail addresses are not broken up into their user@ and
374 domain constituent parts, nor is user+foo broken up into user and foo.
375 Patterns are applied in the order as specified in the table, until a
377 pattern is found that matches the search string.
378 Actions are the same as with indexed file lookups, with the additional
380 feature that parenthesized substrings from the pattern can be interpo‐
381 lated as $1, $2 and so on.
382
384 This section describes how the table lookups change when lookups are
385 directed to a TCP-based server. For a description of the TCP
386 client/server lookup protocol, see tcp_table(5). This feature is not
387 available up to and including Postfix version 2.4.
388 Each lookup operation uses the entire query string once. Depending on
390 the application, that string is an entire client hostname, an entire
391 client IP address, or an entire mail address. Thus, no parent domain
392 or parent network search is done, user@domain mail addresses are not
393 broken up into their user@ and domain constituent parts, nor is
394 user+foo broken up into user and foo.
395 Actions are the same as with indexed file lookups.
397
399 The following example uses an indexed file, so that the order of table
400 entries does not matter. The example permits access by the client at
401 address 1.2.3.4 but rejects all other clients in 1.2.3.0/24. Instead of
402 hash lookup tables, some systems use dbm. Use the command "postconf
403 -m" to find out what lookup tables Postfix supports on your system.
404 /etc/postfix/main.cf:
406 smtpd_client_restrictions =
407 check_client_access hash:/etc/postfix/access
408 /etc/postfix/access:
410 1.2.3 REJECT
411 1.2.3.4 OK
412 Execute the command "postmap /etc/postfix/access" after editing the
414 file.
415
417 The table format does not understand quoting conventions.
418
420 postmap(1), Postfix lookup table manager
421 smtpd(8), SMTP server
422 postconf(5), configuration parameters
423 transport(5), transport:nexthop syntax
424
426 Use "postconf readme_directory" or "postconf html_directory" to locate
427 this information.
428 SMTPD_ACCESS_README, built-in SMTP server access control
429 DATABASE_README, Postfix lookup table overview
430
432 The Secure Mailer license must be distributed with this software.
433
435 Wietse Venema
436 IBM T.J. Watson Research
437 P.O. Box 704
438 Yorktown Heights, NY 10598, USA
439 Wietse Venema
441 Google, Inc.
442 111 8th Avenue
443 New York, NY 10011, USA
444 ACCESS(5)