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 (note that
72 this is the default for some versions of Postfix). Otherwise,
73 specify .domain.tld (note the initial dot) in order to match
74 subdomains.
75 user@ Matches all mail addresses with the specified user part.
77 Note: lookup of the null sender address is not possible with some types
79 of lookup table. By default, Postfix uses <> as the lookup key for such
80 addresses. The value is specified with the smtpd_null_access_lookup_key
81 parameter in the Postfix main.cf file.
82
84 When a mail address localpart contains the optional recipient delimiter
85 (e.g., user+foo@domain), the lookup order becomes: user+foo@domain,
86 user@domain, domain, user+foo@, and user@.
87
89 With lookups from indexed files such as DB or DBM, or from networked
90 tables such as NIS, LDAP or SQL, the following lookup patterns are
91 examined in the order as listed:
92 domain.tld
94 Matches domain.tld.
95 The pattern domain.tld also matches subdomains, but only when
97 the string smtpd_access_maps is listed in the Postfix par‐
98 ent_domain_matches_subdomains configuration setting. Otherwise,
99 specify .domain.tld (note the initial dot) in order to match
100 subdomains.
101 net.work.addr.ess
103 net.work.addr
105 net.work
107 net Matches the specified IPv4 host address or subnetwork. An IPv4
109 host address is a sequence of four decimal octets separated by
110 ".".
111 Subnetworks are matched by repeatedly truncating the last
113 ".octet" from the remote IPv4 host address string until a match
114 is found in the access table, or until further truncation is not
115 possible.
116 NOTE 1: The access map lookup key must be in canonical form: do
118 not specify unnecessary null characters, and do not enclose net‐
119 work address information with "[]" characters.
120 NOTE 2: use the cidr lookup table type to specify network/net‐
122 mask patterns. See cidr_table(5) for details.
123 net:work:addr:ess
125 net:work:addr
127 net:work
129 net Matches the specified IPv6 host address or subnetwork. An IPv6
131 host address is a sequence of three to eight hexadecimal octet
132 pairs separated by ":".
133 Subnetworks are matched by repeatedly truncating the last
135 ":octetpair" from the remote IPv6 host address string until a
136 match is found in the access table, or until further truncation
137 is not possible.
138 NOTE 1: the truncation and comparison are done with the string
140 representation of the IPv6 host address. Thus, not all the ":"
141 subnetworks will be tried.
142 NOTE 2: The access map lookup key must be in canonical form: do
144 not specify unnecessary null characters, and do not enclose net‐
145 work address information with "[]" characters.
146 NOTE 3: use the cidr lookup table type to specify network/net‐
148 mask patterns. See cidr_table(5) for details.
149 IPv6 support is available in Postfix 2.2 and later.
151
153 OK Accept the address etc. that matches the pattern.
154 all-numerical
156 An all-numerical result is treated as OK. This format is gener‐
157 ated by address-based relay authorization schemes such as pop-
158 before-smtp.
159
161 Postfix version 2.3 and later support enhanced status codes as defined
162 in RFC 3463. When no code is specified at the beginning of the text
163 below, Postfix inserts a default enhanced status code of "5.7.1" in the
164 case of reject actions, and "4.7.1" in the case of defer actions. See
165 "ENHANCED STATUS CODES" below.
166 4NN text
168 5NN text
170 Reject the address etc. that matches the pattern, and respond
171 with the numerical three-digit code and text. 4NN means "try
172 again later", while 5NN means "do not try again".
173 The reply code "421" causes Postfix to disconnect immediately
175 (Postfix version 2.3 and later).
176 REJECT optional text...
178 Reject the address etc. that matches the pattern. Reply with
179 $reject_code optional text... when the optional text is speci‐
180 fied, otherwise reply with a generic error response message.
181 DEFER_IF_REJECT optional text...
183 Defer the request if some later restriction would result in a
184 REJECT action. Reply with "450 4.7.1 optional text... when the
185 optional text is specified, otherwise reply with a generic error
186 response message.
187 This feature is available in Postfix 2.1 and later.
189 DEFER_IF_PERMIT optional text...
191 Defer the request if some later restriction would result in a an
192 explicit or implicit PERMIT action. Reply with "450 4.7.1
193 optional text... when the optional text is specified, otherwise
194 reply with a generic error response message.
195 This feature is available in Postfix 2.1 and later.
197
199 restriction...
200 Apply the named UCE restriction(s) (permit, reject,
201 reject_unauth_destination, and so on).
202 DISCARD optional text...
204 Claim successful delivery and silently discard the message. Log
205 the optional text if specified, otherwise log a generic message.
206 Note: this action currently affects all recipients of the mes‐
208 sage. To discard only one recipient without discarding the
209 entire message, use the transport(5) table to direct mail to the
210 discard(8) service.
211 This feature is available in Postfix 2.0 and later.
213 DUNNO Pretend that the lookup key was not found. This prevents Postfix
215 from trying substrings of the lookup key (such as a subdomain
216 name, or a network address subnetwork).
217 This feature is available in Postfix 2.0 and later.
219 FILTER transport:destination
221 After the message is queued, send the entire message through the
222 specified external content filter. The transport:destination
223 syntax is described in the transport(5) manual page. More
224 information about external content filters is in the Postfix
225 FILTER_README file.
226 Note: this action overrides the content_filter setting, and cur‐
228 rently affects all recipients of the message.
229 This feature is available in Postfix 2.0 and later.
231 HOLD optional text...
233 Place the message on the hold queue, where it will sit until
234 someone either deletes it or releases it for delivery. Log the
235 optional text if specified, otherwise log a generic message.
236 Mail that is placed on hold can be examined with the postcat(1)
238 command, and can be destroyed or released with the postsuper(1)
239 command.
240 Note: use "postsuper -r" to release mail that was kept on hold
242 for a significant fraction of $maximal_queue_lifetime or
243 $bounce_queue_lifetime, or longer. Use "postsuper -H" only for
244 mail that will not expire within a few delivery attempts.
245 Note: this action currently affects all recipients of the mes‐
247 sage.
248 This feature is available in Postfix 2.0 and later.
250 PREPEND headername: headervalue
252 Prepend the specified message header to the message. When more
253 than one PREPEND action executes, the first prepended header
254 appears before the second etc. prepended header.
255 Note: this action must execute before the message content is
257 received; it cannot execute in the context of
258 smtpd_end_of_data_restrictions.
259 This feature is available in Postfix 2.1 and later.
261 REDIRECT user@domain
263 After the message is queued, send the message to the specified
264 address instead of the intended recipient(s).
265 Note: this action overrides the FILTER action, and currently
267 affects all recipients of the message.
268 This feature is available in Postfix 2.1 and later.
270 WARN optional text...
272 Log a warning with the optional text, together with client
273 information and if available, with helo, sender, recipient and
274 protocol information.
275 This feature is available in Postfix 2.1 and later.
277
279 Postfix version 2.3 and later support enhanced status codes as defined
280 in RFC 3463. When an enhanced status code is specified in an access
281 table, it is subject to modification. The following transformations are
282 needed when the same access table is used for client, helo, sender, or
283 recipient access restrictions; they happen regardless of whether Post‐
284 fix replies to a MAIL FROM, RCPT TO or other SMTP command.
285 · When a sender address matches a REJECT action, the Postfix SMTP
287 server will transform a recipient DSN status (e.g., 4.1.1-4.1.6)
288 into the corresponding sender DSN status, and vice versa.
289 · When non-address information matches a REJECT action (such as
291 the HELO command argument or the client hostname/address), the
292 Postfix SMTP server will transform a sender or recipient DSN
293 status into a generic non-address DSN status (e.g., 4.0.0).
294
296 This section describes how the table lookups change when the table is
297 given in the form of regular expressions. For a description of regular
298 expression lookup table syntax, see regexp_table(5) or pcre_table(5).
299 Each pattern is a regular expression that is applied to the entire
301 string being looked up. Depending on the application, that string is an
302 entire client hostname, an entire client IP address, or an entire mail
303 address. Thus, no parent domain or parent network search is done,
304 user@domain mail addresses are not broken up into their user@ and
305 domain constituent parts, nor is user+foo broken up into user and foo.
306 Patterns are applied in the order as specified in the table, until a
308 pattern is found that matches the search string.
309 Actions are the same as with indexed file lookups, with the additional
311 feature that parenthesized substrings from the pattern can be interpo‐
312 lated as $1, $2 and so on.
313
315 This section describes how the table lookups change when lookups are
316 directed to a TCP-based server. For a description of the TCP
317 client/server lookup protocol, see tcp_table(5). This feature is not
318 available up to and including Postfix version 2.4.
319 Each lookup operation uses the entire query string once. Depending on
321 the application, that string is an entire client hostname, an entire
322 client IP address, or an entire mail address. Thus, no parent domain
323 or parent network search is done, user@domain mail addresses are not
324 broken up into their user@ and domain constituent parts, nor is
325 user+foo broken up into user and foo.
326 Actions are the same as with indexed file lookups.
328
330 The following example uses an indexed file, so that the order of table
331 entries does not matter. The example permits access by the client at
332 address 1.2.3.4 but rejects all other clients in 1.2.3.0/24. Instead of
333 hash lookup tables, some systems use dbm. Use the command "postconf
334 -m" to find out what lookup tables Postfix supports on your system.
335 /etc/postfix/main.cf:
337 smtpd_client_restrictions =
338 check_client_access hash:/etc/postfix/access
339 /etc/postfix/access:
341 1.2.3 REJECT
342 1.2.3.4 OK
343 Execute the command "postmap /etc/postfix/access" after editing the
345 file.
346
348 The table format does not understand quoting conventions.
349
351 postmap(1), Postfix lookup table manager
352 smtpd(8), SMTP server
353 postconf(5), configuration parameters
354 transport(5), transport:nexthop syntax
355
357 Use "postconf readme_directory" or "postconf html_directory" to locate
358 this information.
359 SMTPD_ACCESS_README, built-in SMTP server access control
360 DATABASE_README, Postfix lookup table overview
361
363 The Secure Mailer license must be distributed with this software.
364
366 Wietse Venema
367 IBM T.J. Watson Research
368 P.O. Box 704
369 Yorktown Heights, NY 10598, USA
370 ACCESS(5)