Postfix manual - access(5)

    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 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 /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.

           For other accept actions, see "OTHER ACTIONS" below.

    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.

           For other reject actions, see "OTHER ACTIONS" below.

    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 available in Postfix 3.0 and later.

           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).  When multiple RE-
                  DIRECT actions fire, only the last one takes effect.

                  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.

           INFO optional text...
                  Log  an  informational  record  with the optional text, together
                  with client information and if  available,  with  helo,  sender,
                  recipient and protocol information.

                  This feature is available in Postfix 3.0 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.

           o      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.

           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 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.

           /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

           Wietse Venema
           Google, Inc.
           111 8th Avenue
           New York, NY 10011, USA

                                                                         ACCESS(5)