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ACCESS(5)							     ACCESS(5)

NAME
       access - Postfix SMTP server access table

SYNOPSIS
       postmap /usr/local/etc/postfix/access

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

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

DESCRIPTION
       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
       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  /usr/local/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 corresponding 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 par‐
	      ent_domain_matches_subdomains configuration setting.

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

       .domain.tld
	      Matches  subdomains  of  domain.tld,  but	 only  when the string
	      smtpd_access_maps	 is   not   listed   in	  the	Postfix	  par‐
	      ent_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 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 cidr lookup table type to	 specify  network/net‐
	      mask 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 unnecessary null characters, and do not enclose net‐
	      work address information with "[]" characters.

	      NOTE 3: use the cidr lookup table type to	 specify  network/net‐
	      mask 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 gener‐
	      ated 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  con‐
		     cern.   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, otherwise reply with a generic error response mes‐
	      sage.

	      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  mes‐
	      sage.   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 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.

       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 mas‐
	      ter.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 destination unless you know	that  the  information
	      has a trusted origin.

	      Note  2:	this  action overrides the main.cf content_filter set‐
	      ting, and affects all recipients of the  message.	 In  the  case
	      that  multiple  FILTER  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	 transport but not the
	      next-hop destination, specify an empty filter destination (Post‐
	      fix  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 trans‐
	      port_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  mes‐
	      sage.

	      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 Post‐
       fix replies to a MAIL FROM, RCPT TO or other SMTP command.

       ·      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.

       ·      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 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  interpo‐
       lated 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_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.

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  command  "postconf
       -m" to find out what lookup tables Postfix supports on your system.

       /usr/local/etc/postfix/main.cf:
	   smtpd_client_restrictions =
	       check_client_access hash:$config_directory/access

       /usr/local/etc/postfix/access:
	   1.2.3   REJECT
	   1.2.3.4 OK

       Execute the command "postmap /usr/local/etc/postfix/access" after edit‐
       ing 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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