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ACCESS(5) ACCESS(5)
<b>NAME</b>
access - Postfix SMTP server access table
<b>SYNOPSIS</b>
<b>postmap /etc/postfix/access</b>
<b>postmap -q "</b><i>string</i><b>" /etc/postfix/access</b>
<b>postmap -q - /etc/postfix/access</b> <<i>inputfile</i>
<b>DESCRIPTION</b>
This document describes access control on remote SMTP client informa-
tion: host names, network addresses, and envelope sender or recipient
addresses; it is implemented by the Postfix SMTP server. See
<a href="header_checks.5.html"><b>header_checks</b>(5)</a> or <a href="header_checks.5.html"><b>body_checks</b>(5)</a> for access control on the content of
email messages.
Normally, the <a href="access.5.html"><b>access</b>(5)</a> table is specified as a text file that serves
as input to the <a href="postmap.1.html"><b>postmap</b>(1)</a> command. The result, an indexed file in <b>dbm</b>
or <b>db</b> format, is used for fast searching by the mail system. Execute
the command "<b>postmap /etc/postfix/access</b>" 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".
<b>CASE FOLDING</b>
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 <a href="regexp_table.5.html">regexp</a>: or <a href="pcre_table.5.html">pcre</a>: whose lookup fields can match both upper and
lower case.
<b>TABLE FORMAT</b>
The input format for the <a href="postmap.1.html"><b>postmap</b>(1)</a> command is as follows:
<i>pattern action</i>
When <i>pattern</i> matches a mail address, domain or host address,
perform the corresponding <i>action</i>.
blank lines and comments
Empty lines and whitespace-only lines are ignored, as are lines
whose first non-whitespace character is a `#'.
multi-line text
A logical line starts with non-whitespace text. A line that
starts with whitespace continues a logical line.
<b>EMAIL ADDRESS PATTERNS</b>
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:
<i>user</i>@<i>domain</i>
Matches the specified mail address.
<i>domain.tld</i>
Matches <i>domain.tld</i> as the domain part of an email address.
The pattern <i>domain.tld</i> also matches subdomains, but only when
the string <b>smtpd_access_maps</b> is listed in the Postfix <b><a href="postconf.5.html#parent_domain_matches_subdomains">par</a>-</b>
<b><a href="postconf.5.html#parent_domain_matches_subdomains">ent_domain_matches_subdomains</a></b> configuration setting.
<i>.domain.tld</i>
Matches subdomains of <i>domain.tld</i>, but only when the string
<b>smtpd_access_maps</b> is not listed in the Postfix <b><a href="postconf.5.html#parent_domain_matches_subdomains">par</a>-</b>
<b><a href="postconf.5.html#parent_domain_matches_subdomains">ent_domain_matches_subdomains</a></b> configuration setting.
<i>user</i>@ Matches all mail addresses with the specified user part.
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 <b><a href="postconf.5.html#smtpd_null_access_lookup_key">smtpd_null_access_lookup_key</a></b>
parameter in the Postfix <a href="postconf.5.html"><b>main.cf</b></a> file.
<b>EMAIL ADDRESS EXTENSION</b>
When a mail address localpart contains the optional recipient delimiter
(e.g., <i>user+foo</i>@<i>domain</i>), the lookup order becomes: <i>user+foo</i>@<i>domain</i>,
<i>user</i>@<i>domain</i>, <i>domain</i>, <i>user+foo</i>@, and <i>user</i>@.
<b>HOST NAME/ADDRESS PATTERNS</b>
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:
<i>domain.tld</i>
Matches <i>domain.tld</i>.
The pattern <i>domain.tld</i> also matches subdomains, but only when
the string <b>smtpd_access_maps</b> is listed in the Postfix <b><a href="postconf.5.html#parent_domain_matches_subdomains">par</a>-</b>
<b><a href="postconf.5.html#parent_domain_matches_subdomains">ent_domain_matches_subdomains</a></b> configuration setting.
<i>.domain.tld</i>
Matches subdomains of <i>domain.tld</i>, but only when the string
<b>smtpd_access_maps</b> is not listed in the Postfix <b><a href="postconf.5.html#parent_domain_matches_subdomains">par</a>-</b>
<b><a href="postconf.5.html#parent_domain_matches_subdomains">ent_domain_matches_subdomains</a></b> configuration setting.
<i>net.work.addr.ess</i>
<i>net.work.addr</i>
<i>net.work</i>
<i>net</i> Matches the specified IPv4 host address or subnetwork. An IPv4
host address is a sequence of four decimal octets separated by
".".
Subnetworks are matched by repeatedly truncating the last
".octet" from the remote IPv4 host address string until a match
is found in the access table, or until further truncation is not
possible.
NOTE 1: The access map lookup key must be in canonical form: do
not specify unnecessary null characters, and do not enclose net-
work address information with "[]" characters.
NOTE 2: use the <b>cidr</b> lookup table type to specify network/net-
mask patterns. See <a href="cidr_table.5.html"><b>cidr_table</b>(5)</a> for details.
<i>net:work:addr:ess</i>
<i>net:work:addr</i>
<i>net:work</i>
<i>net</i> Matches the specified IPv6 host address or subnetwork. An IPv6
host address is a sequence of three to eight hexadecimal octet
pairs separated by ":".
Subnetworks are matched by repeatedly truncating the last
":octetpair" from the remote IPv6 host address string until a
match is found in the access table, or until further truncation
is not possible.
NOTE 1: the truncation and comparison are done with the string
representation of the IPv6 host address. Thus, not all the ":"
subnetworks will be tried.
NOTE 2: The access map lookup key must be in canonical form: do
not specify unnecessary null characters, and do not enclose net-
work address information with "[]" characters.
NOTE 3: use the <b>cidr</b> lookup table type to specify network/net-
mask patterns. See <a href="cidr_table.5.html"><b>cidr_table</b>(5)</a> for details.
IPv6 support is available in Postfix 2.2 and later.
<b>ACCEPT ACTIONS</b>
<b>OK</b> Accept the address etc. that matches the pattern.
<i>all-numerical</i>
An all-numerical result is treated as OK. This format is gener-
ated by address-based relay authorization schemes such as pop-
before-smtp.
For other accept actions, see "OTHER ACTIONS" below.
<b>REJECT ACTIONS</b>
Postfix version 2.3 and later support enhanced status codes as defined
in <a href="http://tools.ietf.org/html/rfc3463">RFC 3463</a>. When no code is specified at the beginning of the <i>text</i>
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.
<b>4</b><i>NN text</i>
<b>5</b><i>NN text</i>
Reject the address etc. that matches the pattern, and respond
with the numerical three-digit code and text. <b>4</b><i>NN</i> means "try
again later", while <b>5</b><i>NN</i> means "do not try again".
The following responses have special meaning for the Postfix
SMTP server:
<b>421</b> <i>text</i> (Postfix 2.3 and later)
<b>521</b> <i>text</i> (Postfix 2.6 and later)
After responding with the numerical three-digit code and
text, disconnect immediately from the SMTP client. This
frees up SMTP server resources so that they can be made
available to another SMTP client.
Note: The "521" response should be used only with botnets
and other malware where interoperability is of no con-
cern. The "send 521 and disconnect" behavior is NOT
defined in the SMTP standard.
<b>REJECT</b> <i>optional text...</i>
Reject the address etc. that matches the pattern. Reply with
"<b>$<a href="postconf.5.html#access_map_reject_code">access_map_reject_code</a></b> <i>optional text...</i>" when the optional
text is specified, otherwise reply with a generic error response
message.
<b>DEFER</b> <i>optional text...</i>
Reject the address etc. that matches the pattern. Reply with
"<b>$<a href="postconf.5.html#access_map_defer_code">access_map_defer_code</a></b> <i>optional text...</i>" when the optional text
is specified, otherwise reply with a generic error response mes-
sage.
This feature is available in Postfix 2.6 and later.
<b>DEFER_IF_REJECT</b> <i>optional text...</i>
Defer the request if some later restriction would result in a
REJECT action. Reply with "<b>$<a href="postconf.5.html#access_map_defer_code">access_map_defer_code</a> 4.7.1</b> <i>optional</i>
<i>text...</i>" when the optional text is specified, otherwise reply
with a generic error response message.
Prior to Postfix 2.6, the SMTP reply code is 450.
This feature is available in Postfix 2.1 and later.
<b>DEFER_IF_PERMIT</b> <i>optional text...</i>
Defer the request if some later restriction would result in a an
explicit or implicit PERMIT action. Reply with
"<b>$<a href="postconf.5.html#access_map_defer_code">access_map_defer_code</a> 4.7.1</b> <i>optional text...</i>" when the
optional text is specified, otherwise reply with a generic error
response message.
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.
<b>OTHER ACTIONS</b>
<i>restriction...</i>
Apply the named UCE restriction(s) (<b>permit</b>, <b>reject</b>,
<b><a href="postconf.5.html#reject_unauth_destination">reject_unauth_destination</a></b>, and so on).
<b>BCC</b> <i>user@domain</i>
Send one copy of the message to the specified recipient.
If multiple BCC actions are specified within the same SMTP MAIL
transaction, only the last action will be used.
This feature is not part of the stable Postfix release.
<b>DISCARD</b> <i>optional text...</i>
Claim successful delivery and silently discard the message. Log
the optional text if specified, otherwise log a generic message.
Note: this action currently affects all recipients of the mes-
sage. To discard only one recipient without discarding the
entire message, use the <a href="transport.5.html">transport(5)</a> table to direct mail to the
<a href="discard.8.html">discard(8)</a> service.
This feature is available in Postfix 2.0 and later.
<b>DUNNO</b> Pretend that the lookup key was not found. This prevents Postfix
from trying substrings of the lookup key (such as a subdomain
name, or a network address subnetwork).
This feature is available in Postfix 2.0 and later.
<b>FILTER</b> <i>transport:destination</i>
After the message is queued, send the entire message through the
specified external content filter. The <i>transport</i> name specifies
the first field of a mail delivery agent definition in <a href="master.5.html">mas-
ter.cf</a>; the syntax of the next-hop <i>destination</i> is described in
the manual page of the corresponding delivery agent. More
information about external content filters is in the Postfix
<a href="FILTER_README.html">FILTER_README</a> file.
Note 1: do not use $<i>number</i> regular expression substitutions for
<i>transport</i> or <i>destination</i> unless you know that the information
has a trusted origin.
Note 2: this action overrides the <a href="postconf.5.html">main.cf</a> <b><a href="postconf.5.html#content_filter">content_filter</a></b> set-
ting, and affects all recipients of the message. In the case
that multiple <b>FILTER</b> actions fire, only the last one is exe-
cuted.
Note 3: the purpose of the FILTER command is to override message
routing. To override the recipient's <i>transport</i> but not the
next-hop <i>destination</i>, specify an empty filter <i>destination</i> (Post-
fix 2.7 and later), or specify a <i>transport:destination</i> that
delivers through a different Postfix instance (Postfix 2.6 and
earlier). Other options are using the recipient-dependent <b><a href="postconf.5.html#transport_maps">trans</a>-</b>
<b><a href="postconf.5.html#transport_maps">port_maps</a></b> or the sender-dependent <b><a href="postconf.5.html#sender_dependent_default_transport_maps">sender_dependent_default-</b>
<b>_transport_maps</a></b> features.
This feature is available in Postfix 2.0 and later.
<b>HOLD</b> <i>optional text...</i>
Place the message on the <b>hold</b> queue, where it will sit until
someone either deletes it or releases it for delivery. Log the
optional text if specified, otherwise log a generic message.
Mail that is placed on hold can be examined with the <a href="postcat.1.html"><b>postcat</b>(1)</a>
command, and can be destroyed or released with the <a href="postsuper.1.html"><b>postsuper</b>(1)</a>
command.
Note: use "<b>postsuper -r</b>" to release mail that was kept on hold
for a significant fraction of <b>$<a href="postconf.5.html#maximal_queue_lifetime">maximal_queue_lifetime</a></b> or
<b>$<a href="postconf.5.html#bounce_queue_lifetime">bounce_queue_lifetime</a></b>, or longer. Use "<b>postsuper -H</b>" only for
mail that will not expire within a few delivery attempts.
Note: this action currently affects all recipients of the mes-
sage.
This feature is available in Postfix 2.0 and later.
<b>PREPEND</b> <i>headername: headervalue</i>
Prepend the specified message header to the message. When more
than one PREPEND action executes, the first prepended header
appears before the second etc. prepended header.
Note: this action must execute before the message content is
received; it cannot execute in the context of
<b><a href="postconf.5.html#smtpd_end_of_data_restrictions">smtpd_end_of_data_restrictions</a></b>.
This feature is available in Postfix 2.1 and later.
<b>REDIRECT</b> <i>user@domain</i>
After the message is queued, send the message to the specified
address instead of the intended recipient(s).
Note: this action overrides the FILTER action, and currently
affects all recipients of the message.
This feature is available in Postfix 2.1 and later.
<b>WARN</b> <i>optional text...</i>
Log a warning with the optional text, together with client
information and if available, with helo, sender, recipient and
protocol information.
This feature is available in Postfix 2.1 and later.
<b>ENHANCED STATUS CODES</b>
Postfix version 2.3 and later support enhanced status codes as defined
in <a href="http://tools.ietf.org/html/rfc3463">RFC 3463</a>. 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 Post-
fix replies to a MAIL FROM, RCPT TO or other SMTP command.
<b>o</b> When a sender address matches a REJECT action, the Postfix SMTP
server will transform a recipient DSN status (e.g., 4.1.1-4.1.6)
into the corresponding sender DSN status, and vice versa.
<b>o</b> When non-address information matches a REJECT action (such as
the HELO command argument or the client hostname/address), the
Postfix SMTP server will transform a sender or recipient DSN
status into a generic non-address DSN status (e.g., 4.0.0).
<b>REGULAR EXPRESSION TABLES</b>
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 <a href="regexp_table.5.html"><b>regexp_table</b>(5)</a> or <a href="pcre_table.5.html"><b>pcre_table</b>(5)</a>.
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,
<i>user@domain</i> mail addresses are not broken up into their <i>user@</i> and
<i>domain</i> constituent parts, nor is <i>user+foo</i> broken up into <i>user</i> and <i>foo</i>.
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 interpo-
lated as <b>$1</b>, <b>$2</b> and so on.
<b>TCP-BASED TABLES</b>
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 <a href="tcp_table.5.html"><b>tcp_table</b>(5)</a>. 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, <i>user@domain</i> mail addresses are not
broken up into their <i>user@</i> and <i>domain</i> constituent parts, nor is
<i>user+foo</i> broken up into <i>user</i> and <i>foo</i>.
Actions are the same as with indexed file lookups.
<b>EXAMPLE</b>
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
<b>hash</b> lookup tables, some systems use <b>dbm</b>. Use the command "<b>postconf</b>
<b>-m</b>" to find out what lookup tables Postfix supports on your system.
/etc/postfix/<a href="postconf.5.html">main.cf</a>:
<a href="postconf.5.html#smtpd_client_restrictions">smtpd_client_restrictions</a> =
<a href="postconf.5.html#check_client_access">check_client_access</a> <a href="DATABASE_README.html#types">hash</a>:/etc/postfix/access
/etc/postfix/access:
1.2.3 REJECT
1.2.3.4 OK
Execute the command "<b>postmap /etc/postfix/access</b>" after editing the
file.
<b>BUGS</b>
The table format does not understand quoting conventions.
<b>SEE ALSO</b>
<a href="postmap.1.html">postmap(1)</a>, Postfix lookup table manager
<a href="smtpd.8.html">smtpd(8)</a>, SMTP server
<a href="postconf.5.html">postconf(5)</a>, configuration parameters
<a href="transport.5.html">transport(5)</a>, transport:nexthop syntax
<b>README FILES</b>
<a href="SMTPD_ACCESS_README.html">SMTPD_ACCESS_README</a>, built-in SMTP server access control
<a href="DATABASE_README.html">DATABASE_README</a>, Postfix lookup table overview
<b>LICENSE</b>
The Secure Mailer license must be distributed with this software.
<b>AUTHOR(S)</b>
Wietse Venema
IBM T.J. Watson Research
P.O. Box 704
Yorktown Heights, NY 10598, USA
ACCESS(5)
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