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 to create an indexed file  for  fast
           lookup.

           Execute   the   command  "postmap  /etc/postfix/access"  to  rebuild  a
           default-type indexed file after changing  the  text  file,  or  execute
           "postmap type:/etc/postfix/access" to specify an explicit type.

           The  default  indexed  file  type  is configured with the default_data-
           base_type parameter. Depending on the  platform  this  may  be  one  of
           lmdb:, cdb:, hash:, or dbm: (without the trailing ':').

           When  the  table  is provided via other means such as NIS, LDAP or SQL,
           the same lookups are done as for ordinary indexed files.  Managing such
           databases is outside the scope of Postfix.

           Alternatively,  the  table  can be provided as a regular-expression map
           where patterns are given as regular  expressions,  or  lookups  can  be
           directed to a 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 IN INDEXED TABLES
           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 IN INDEXED TABLES
           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 a remote IPv4 host address  or  network  address  range.
                  Specify  one  to  four  decimal  octets separated by ".". Do not
                  specify "[]" , "/", leading zeros, or hexadecimal forms.

                  Network ranges are matched by  repeatedly  truncating  the  last
                  ".octet"  from  a remote IPv4 host address string, until a match
                  is found in the access table, or until further truncation is not
                  possible.

                  NOTE:  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 a remote IPv6 host address  or  network  address  range.
                  Specify three to eight hexadecimal octet pairs separated by ":",
                  using the compressed form "::" for  a  sequence  of  zero-valued
                  octet  pairs.  Do  not  specify  "[]",  "/",  leading  zeros, or
                  non-compressed forms.

                  A network range is matched by  repeatedly  truncating  the  last
                  ":octetpair"  from  the compressed-form remote IPv6 host address
                  string, until a match is found in the  access  table,  or  until
                  further truncation is not possible.

                  NOTE:  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  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  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, with Postfix 3.0 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 1: this action overrides the FILTER action,  and  currently
                  overrides all recipients of the message.

                  Note  2:  a REDIRECT address is subject to canonicalization (add
                  missing domain) but NOT subject to canonical,  masquerade,  bcc,
                  or virtual alias mapping.

                  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)