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ACCESS(5)										ACCESS(5)

NAME
       access - Postfix SMTP server access table

SYNOPSIS
       postmap /etc/postfix/access

       postmap -q "string" /etc/postfix/access

       postmap -q - /etc/postfix/access <inputfile

DESCRIPTION
       This document describes access control on remote SMTP client information: host names, net-
       work addresses, and envelope sender or recipient addresses; it is implemented by the Post-
       fix SMTP server.  See header_checks(5) or body_checks(5) for access control on the content
       of email messages.

       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".

CASE FOLDING
       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.

TABLE FORMAT
       The input format for the postmap(1) command is as follows:

       pattern action
	      When  pattern  matches  a  mail address, domain or host address, perform the corre-
	      sponding action.

       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.

EMAIL ADDRESS PATTERNS
       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:

       user@domain
	      Matches the specified mail address.

       domain.tld
	      Matches domain.tld as the domain part of an email address.

	      The   pattern  domain.tld  also  matches	subdomains,  but  only	when  the  string
	      smtpd_access_maps is listed in the Postfix parent_domain_matches_subdomains config-
	      uration setting.

       .domain.tld
	      Matches subdomains of domain.tld, but only when the string smtpd_access_maps is not
	      listed in the Postfix parent_domain_matches_subdomains configuration setting.

       user@  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 smtpd_null_access_lookup_key parameter in the Postfix main.cf file.

EMAIL ADDRESS EXTENSION
       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@.

HOST NAME/ADDRESS PATTERNS
       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:

       domain.tld
	      Matches domain.tld.

	      The   pattern  domain.tld  also  matches	subdomains,  but  only	when  the  string
	      smtpd_access_maps is listed in the Postfix parent_domain_matches_subdomains config-
	      uration setting.

       .domain.tld
	      Matches subdomains of domain.tld, but only when the string smtpd_access_maps is not
	      listed in the Postfix parent_domain_matches_subdomains configuration setting.

       net.work.addr.ess

       net.work.addr

       net.work

       net    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  fur-
	      ther truncation is not possible.

	      NOTE  1: The access map lookup key must be in canonical form: do not specify unnec-
	      essary null characters, and do not enclose network address  information  with  "[]"
	      characters.

	      NOTE  2:	use  the  cidr lookup table type to specify network/netmask patterns. See
	      cidr_table(5) for details.

       net:work:addr:ess

       net:work:addr

       net:work

       net    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  unnec-
	      essary  null  characters,  and do not enclose network address information with "[]"
	      characters.

	      NOTE 3: 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.

ACCEPT ACTIONS
       OK     Accept the address etc. that matches the pattern.

       all-numerical
	      An all-numerical result is treated as OK. This format is generated by address-based
	      relay authorization schemes such as pop-before-smtp.

REJECT ACTIONS
       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.

       4NN text

       5NN text
	      Reject  the  address  etc. that matches the pattern, and respond with the numerical
	      three-digit code and text. 4NN means "try again later", while 5NN means "do not try
	      again".

	      The following responses have special meaning for the Postfix SMTP server:

	      421 text (Postfix 2.3 and later)

	      521 text (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 concern.	The  "send  521  and  disconnect"
		     behavior is NOT defined in the SMTP standard.

       REJECT optional text...
	      Reject	the    address	  etc.	  that	  matches   the   pattern.   Reply   with
	      "$access_map_reject_code optional text..." when the  optional  text  is  specified,
	      otherwise reply with a generic error response message.

       DEFER optional text...
	      Reject	the    address	  etc.	  that	  matches   the   pattern.   Reply   with
	      "$access_map_defer_code optional text..." when the optional text is specified, oth-
	      erwise reply with a generic error response message.

	      This feature is available in Postfix 2.6 and later.

       DEFER_IF_REJECT optional text...
	      Defer  the request if some later restriction would result in a REJECT action. Reply
	      with "$access_map_defer_code 4.7.1 optional text..."  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.

       DEFER_IF_PERMIT optional text...
	      Defer  the  request  if  some  later  restriction  would result in a an explicit or
	      implicit	PERMIT	action.   Reply  with  "$access_map_defer_code	4.7.1	 optional
	      text..."	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.

OTHER ACTIONS
       restriction...
	      Apply the named UCE restriction(s) (permit, reject, reject_unauth_destination,  and
	      so on).

       BCC user@domain
	      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.

       DISCARD optional text...
	      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 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.

       DUNNO  Pretend  that  the lookup key was not found. This prevents Postfix from trying sub-
	      strings of the lookup key (such as a subdomain name, or a network  address  subnet-
	      work).

	      This feature is available in Postfix 2.0 and later.

       FILTER transport:destination
	      After the message is queued, send the entire message through the specified external
	      content filter. The transport name specifies the first field  of	a  mail  delivery
	      agent  definition in master.cf; the syntax of the next-hop destination is described
	      in the manual page of the corresponding delivery	agent.	 More  information  about
	      external content filters is in the Postfix FILTER_README file.

	      Note 1: do not use $number regular expression substitutions for transport or desti-
	      nation 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 over-
	      ride  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.

       HOLD optional text...
	      Place the message on the hold 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 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.

       PREPEND headername: headervalue
	      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 smtpd_end_of_data_restrictions.

	      This feature is available in Postfix 2.1 and later.

       REDIRECT user@domain
	      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.

       WARN optional text...
	      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.

ENHANCED STATUS CODES
       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.

       o      When a sender address matches a REJECT action, the Postfix SMTP server will  trans-
	      form  a  recipient DSN status (e.g., 4.1.1-4.1.6) into the corresponding sender DSN
	      status, and vice versa.

       o      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).

REGULAR EXPRESSION TABLES
       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 reg-
       exp_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 paren-
       thesized substrings from the pattern can be interpolated as $1, $2 and so on.

TCP-BASED TABLES
       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_ta-
       ble(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.

EXAMPLE
       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  com-
       mand "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.

BUGS
       The table format does not understand quoting conventions.

SEE ALSO
       postmap(1), Postfix lookup table manager
       smtpd(8), SMTP server
       postconf(5), configuration parameters
       transport(5), transport:nexthop syntax

README FILES
       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

LICENSE
       The Secure Mailer license must be distributed with this software.

AUTHOR(S)
       Wietse Venema
       IBM T.J. Watson Research
       P.O. Box 704
       Yorktown Heights, NY 10598, USA

											ACCESS(5)
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