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.

       .domain.tld
              Matches subdomains of domain.tld, but only when the
              string smtpd_access_maps is not listed in the Post‐
              fix parent_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 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.

       .domain.tld
              Matches subdomains of domain.tld, but only when the
              string smtpd_access_maps is not listed in the Post‐
              fix parent_domain_matches_subdomains  configuration
              setting.

       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.

       ·      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 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)