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.

       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)