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)