Postfix manual - access(5)

    ACCESS(5)                                                            ACCESS(5)

    NAME
           access - Postfix access table format

    SYNOPSIS
           postmap /etc/postfix/access

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

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

    DESCRIPTION
           The  optional  access(5)  table  directs  the Postfix SMTP
           server to selectively reject or accept mail. Access can be
           allowed  or  denied for specific host names, domain names,
           networks, host addresses or mail addresses.

           For an example, see the EXAMPLE section at the end of this
           manual page.

           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"  in  order  to  rebuild the
           indexed file after changing the access table.

           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 expres-
           sions, or lookups can be directed to TCP-based server.  In
           that  case,  the  lookups are done in a slightly different
           way as described below under "REGULAR  EXPRESSION  TABLES"
           and "TCP-BASED TABLES".

    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  logi-
                  cal 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  con-
                  figuration  setting  (note that this is the default
                  for some versions of Postfix).  Otherwise,  specify
                  .domain.tld  (note  the  initial  dot)  in order to
                  match subdomains.

           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 recip-
           ient 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  con-
                  figuration setting.  Otherwise, specify .domain.tld
                  (note the initial dot) in  order  to  match  subdo-
                  mains.

           net.work.addr.ess

           net.work.addr

           net.work

           net    Matches  the specified IPv4 host address or subnet-
                  work. 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 information in the access map should be
                  in canonical form, with unnecessary null characters
                  eliminated.   Address  information  must   not   be
                  enclosed 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 subnet-
                  work. 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 information in the access map should be
                  in canonical form, with unnecessary null characters
                  eliminated.   Address  information  must   not   be
                  enclosed 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 for-
                  mat  is generated by address-based relay authoriza-
                  tion schemes.

    REJECT ACTIONS
           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".

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

           DEFER_IF_REJECT optional text...
                  Defer the request if some later  restriction  would
                  result in a REJECT action. Reply with "450 optional
                  text... when the optional text is specified, other-
                  wise reply with a generic error response message.

                  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 "450 optional text... when the  optional
                  text  is  specified, otherwise reply with a generic
                  error response message.

                  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).

           DISCARD optional text...
                  Claim successful delivery and silently discard  the
                  message.   Log the optional text if specified, oth-
                  erwise log a generic message.

                  Note: this action currently affects all  recipients
                  of the message.

                  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  mes-
                  sage through the specified external content filter.
                  The transport:destination syntax  is  described  in
                  the  transport(5)  manual  page.   More information
                  about external content filters is  in  the  Postfix
                  FILTER_README file.

                  Note:   this  action  overrides  the  main.cf  con-
                  tent_filter  setting,  and  currently  affects  all
                  recipients of the message.

                  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  $maxi-
                  mal_queue_lifetime  or  $bounce_queue_lifetime,  or
                  longer.

                  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  mes-
                  sage.  When this action is used multiple times, the
                  first prepended header appears  before  the  second
                  etc. prepended header.

                  Note:  this action does not support multi-line mes-
                  sage headers.

                  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.

    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 appli-
           cation,  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  ta-
           ble,  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.

    TCP-BASED TABLES
           This section describes how the table lookups  change  when
           lookups are directed to a TCP-based server. For a descrip-
           tion of the TCP client/server lookup protocol, see tcp_ta-
           ble(5).  This feature is not available up to and including
           Postfix version 2.2.

           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 per-
           mits 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.

    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
           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)