postmap /etc/postfix/access postmap -q "string" /etc/postfix/access postmap -q - /etc/postfix/access <inputfile
Normally, the access(5) table is specified as a text file that serves as input to the postmap(1) command. The result, an indexed file in dbm or db format, is used for fast searching by the mail system. Execute the command "postmap /etc/postfix/access" to rebuild an indexed file after changing the corresponding text file.
When the table is provided via other means such as NIS, LDAP or SQL, the same lookups are done as for ordinary indexed files.
Alternatively, the table can be provided as a regular-expression map where patterns are given as regular expressions, or lookups can be directed to TCP-based server. In those cases, the lookups are done in a slightly different way as described below under "REGULAR EXPRESSION TABLES" or "TCP-BASED TABLES".
The search string is folded to lowercase before database lookup. As of Postfix 2.3, the search string is not case folded with database types such as regexp: or pcre: whose lookup fields can match both upper and lower case.
The input format for the postmap(1) command is as follows:
With lookups from indexed files such as DB or DBM, or from networked tables such as NIS, LDAP or SQL, patterns are tried in the order as listed below:
The pattern domain.tld also matches subdomains, but only when the string smtpd_access_maps is listed in the Postfix parent_domain_matches_subdomains configuration setting.
Note: lookup of the null sender address is not possible with some types of lookup table. By default, Postfix uses <> as the lookup key for such addresses. The value is specified with the smtpd_null_access_lookup_key parameter in the Postfix main.cf file.
When a mail address localpart contains the optional recipient delimiter (e.g., user+foo@domain), the lookup order becomes: user+foo@domain, user@domain, domain, user+foo@, and user@.
With lookups from indexed files such as DB or DBM, or from networked tables such as NIS, LDAP or SQL, the following lookup patterns are examined in the order as listed:
The pattern domain.tld also matches subdomains, but only when the string smtpd_access_maps is listed in the Postfix parent_domain_matches_subdomains configuration setting.
Network ranges are matched by repeatedly truncating the last ".octet" from a remote IPv4 host address string, until a match is found in the access table, or until further truncation is not possible.
NOTE: use the cidr lookup table type to specify network/netmask patterns. See cidr_table(5) for details.
A network range is matched by repeatedly truncating the last ":octetpair" from the compressed-form remote IPv6 host address string, until a match is found in the access table, or until further truncation is not possible.
NOTE: use the cidr lookup table type to specify network/netmask patterns. See cidr_table(5) for details.
IPv6 support is available in Postfix 2.2 and later.
For other accept actions, see "OTHER ACTIONS" below.
Postfix version 2.3 and later support enhanced status codes as defined in RFC 3463. When no code is specified at the beginning of the text below, Postfix inserts a default enhanced status code of "5.7.1" in the case of reject actions, and "4.7.1" in the case of defer actions. See "ENHANCED STATUS CODES" below.
The following responses have special meaning for the Postfix SMTP server:
This feature is available in Postfix 2.6 and later.
Prior to Postfix 2.6, the SMTP reply code is 450.
This feature is available in Postfix 2.1 and later.
Prior to Postfix 2.6, the SMTP reply code is 450.
This feature is available in Postfix 2.1 and later.
For other reject actions, see "OTHER ACTIONS" below.
If multiple BCC actions are specified within the same SMTP MAIL transaction, with Postfix 3.0 only the last action will be used.
This feature is available in Postfix 3.0 and later.
Note: this action currently affects all recipients of the message. To discard only one recipient without discarding the entire message, use the transport(5) table to direct mail to the discard(8) service.
This feature is available in Postfix 2.0 and later.
This feature is available in Postfix 2.0 and later.
Note 1: do not use $number regular expression substitutions for transport or destination unless you know that the information has a trusted origin.
Note 2: this action overrides the main.cf content_filter setting, and affects all recipients of the message. In the case that multiple FILTER actions fire, only the last one is executed.
Note 3: the purpose of the FILTER command is to override message routing. To override the recipient's transport but not the next-hop destination, specify an empty filter destination (Postfix 2.7 and later), or specify a transport:destination that delivers through a different Postfix instance (Postfix 2.6 and earlier). Other options are using the recipient-dependent transport_maps or the sender-dependent sender_dependent_default_transport_maps features.
This feature is available in Postfix 2.0 and later.
Mail that is placed on hold can be examined with the postcat(1) command, and can be destroyed or released with the postsuper(1) command.
Note: use "postsuper -r" to release mail that was kept on hold for a significant fraction of $maximal_queue_lifetime or $bounce_queue_lifetime, or longer. Use "postsuper -H" only for mail that will not expire within a few delivery attempts.
Note: this action currently affects all recipients of the message.
This feature is available in Postfix 2.0 and later.
Note: this action must execute before the message content is received; it cannot execute in the context of smtpd_end_of_data_restrictions.
This feature is available in Postfix 2.1 and later.
Note: this action overrides the FILTER action, and currently overrides all recipients of the message.
This feature is available in Postfix 2.1 and later.
This feature is available in Postfix 3.0 and later.
This feature is available in Postfix 2.1 and later.
Postfix version 2.3 and later support enhanced status codes as defined in RFC 3463. When an enhanced status code is specified in an access table, it is subject to modification. The following transformations are needed when the same access table is used for client, helo, sender, or recipient access restrictions; they happen regardless of whether Postfix replies to a MAIL FROM, RCPT TO or other SMTP command.
This section describes how the table lookups change when the table is given in the form of regular expressions. For a description of regular expression lookup table syntax, see regexp_table(5) or pcre_table(5).
Each pattern is a regular expression that is applied to the entire string being looked up. Depending on the application, that string is an entire client hostname, an entire client IP address, or an entire mail address. Thus, no parent domain or parent network search is done, user@domain mail addresses are not broken up into their user@ and domain constituent parts, nor is user+foo broken up into user and foo.
Patterns are applied in the order as specified in the table, until a pattern is found that matches the search string.
Actions are the same as with indexed file lookups, with the additional feature that parenthesized substrings from the pattern can be interpolated as $1, $2 and so on.
This section describes how the table lookups change when lookups are directed to a TCP-based server. For a description of the TCP client/server lookup protocol, see tcp_table(5). This feature is not available up to and including Postfix version 2.4.
Each lookup operation uses the entire query string once. Depending on the application, that string is an entire client hostname, an entire client IP address, or an entire mail address. Thus, no parent domain or parent network search is done, user@domain mail addresses are not broken up into their user@ and domain constituent parts, nor is user+foo broken up into user and foo.
Actions are the same as with indexed file lookups.
The following example uses an indexed file, so that the order of table entries does not matter. The example permits access by the client at address 1.2.3.4 but rejects all other clients in 1.2.3.0/24. Instead of hash lookup tables, some systems use dbm. Use the command "postconf -m" to find out what lookup tables Postfix supports on your system.
/etc/postfix/main.cf:
smtpd_client_restrictions =
check_client_access hash:/etc/postfix/access
/etc/postfix/access:
1.2.3 REJECT
1.2.3.4 OK
Execute the command "postmap /etc/postfix/access" after editing the file.
postmap(1), Postfix lookup table manager smtpd(8), SMTP server postconf(5), configuration parameters transport(5), transport:nexthop syntax
Use "postconf readme_directory" or "postconf html_directory" to locate this information.
SMTPD_ACCESS_README, built-in SMTP server access control DATABASE_README, Postfix lookup table overview
The Secure Mailer license must be distributed with this software.
Wietse Venema IBM T.J. Watson Research P.O. Box 704 Yorktown Heights, NY 10598, USA Wietse Venema Google, Inc. 111 8th Avenue New York, NY 10011, USA