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 information: 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 expres-
           sions,  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  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 access map lookup key must be in canon-
                  ical  form: do not specify unnecessary null charac-
                  ters, and do not enclose network  address  informa-
                  tion 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 access map lookup key must be in canon-
                  ical  form: do not specify unnecessary null charac-
                  ters, and do not enclose network  address  informa-
                  tion 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 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  inter-
                         operability 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, oth-
                  erwise 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,  oth-
                  erwise 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, oth-
                  erwise 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  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  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  sub-
                  stitutions  for transport or destination unless you
                  know that the information has a trusted origin.

                  Note 2: this  action  overrides  the  main.cf  con-
                  tent_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 override the  recipi-
                  ent'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  sen-
                  der-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 $maxi-
                  mal_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  mes-
                  sage.   When more than one PREPEND action executes,
                  the first prepended header appears before the  sec-
                  ond etc. prepended header.

                  Note:  this  action must execute before the message
                  content is received; it cannot execute in the  con-
                  text 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 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 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 2.4.

           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 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)