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    Command:

    smtpd

    
    
    

    SYNOPSIS

           smtpd [generic Postfix daemon options]
    
           sendmail -bs
    
    
    

    DESCRIPTION

           The  SMTP  server accepts network connection requests and performs zero
           or more SMTP transactions per connection.   Each  received  message  is
           piped  through  the  cleanup(8) daemon, and is placed into the incoming
           queue as one single queue file.  For this mode of operation,  the  pro-
           gram expects to be run from the master(8) process manager.
    
           Alternatively,  the SMTP server be can run in stand-alone mode; this is
           traditionally obtained with "sendmail -bs".  When the SMTP server  runs
           stand-alone  with  non  $mail_owner  privileges,  it receives mail even
           while the mail system is not running, deposits messages  directly  into
           the  maildrop queue, and disables the SMTP server's access policies. As
           of Postfix version 2.3, the SMTP server refuses to  receive  mail  from
           the network when it runs with non $mail_owner privileges.
    
           The  SMTP  server  implements  a  variety  of  policies  for connection
           requests, and for parameters given to HELO, ETRN, MAIL FROM,  VRFY  and
           RCPT TO commands. They are detailed below and in the main.cf configura-
           tion file.
    
    
    

    SECURITY

           The SMTP server is moderately  security-sensitive.  It  talks  to  SMTP
           clients  and  to DNS servers on the network. The SMTP server can be run
           chrooted at fixed low privilege.
    
    
    

    STANDARDS

           RFC 821 (SMTP protocol)
           RFC 1123 (Host requirements)
           RFC 1652 (8bit-MIME transport)
           RFC 1869 (SMTP service extensions)
           RFC 1870 (Message Size Declaration)
           RFC 1985 (ETRN command)
           RFC 2034 (SMTP Enhanced Error Codes)
           RFC 2554 (AUTH command)
           RFC 2821 (SMTP protocol)
           RFC 2920 (SMTP Pipelining)
           RFC 3207 (STARTTLS command)
           RFC 3461 (SMTP DSN Extension)
           RFC 3463 (Enhanced Status Codes)
           RFC 3848 (ESMTP Transmission Types)
           RFC 4954 (AUTH command)
    
    
    

    DIAGNOSTICS

           Problems and transactions are logged to syslogd(8).
    
           Depending on the setting of the notify_classes parameter, the  postmas-
           ter  is  notified of bounces, protocol problems, policy violations, and
    
           broken_sasl_auth_clients (no)
                  Enable  inter-operability  with  SMTP  clients that implement an
                  obsolete version of the AUTH command (RFC 4954).
    
           disable_vrfy_command (no)
                  Disable the SMTP VRFY command.
    
           smtpd_noop_commands (empty)
                  List of commands that the Postfix SMTP server  replies  to  with
                  "250  Ok",  without doing any syntax checks and without changing
                  state.
    
           strict_rfc821_envelopes (no)
                  Require that addresses received in SMTP MAIL FROM  and  RCPT  TO
                  commands  are  enclosed with <>, and that those addresses do not
                  contain RFC 822 style comments or phrases.
    
           Available in Postfix version 2.1 and later:
    
           resolve_null_domain (no)
                  Resolve an address that ends in the "@" null domain  as  if  the
                  local  hostname were specified, instead of rejecting the address
                  as invalid.
    
           smtpd_reject_unlisted_sender (no)
                  Request that the Postfix SMTP server rejects mail  from  unknown
                  sender  addresses,  even when no explicit reject_unlisted_sender
                  access restriction is specified.
    
           smtpd_sasl_exceptions_networks (empty)
                  What remote SMTP clients the Postfix SMTP server will not  offer
                  AUTH support to.
    
           Available in Postfix version 2.2 and later:
    
           smtpd_discard_ehlo_keyword_address_maps (empty)
                  Lookup  tables,  indexed by the remote SMTP client address, with
                  case insensitive lists of EHLO keywords  (pipelining,  starttls,
                  auth,  etc.)  that  the  SMTP  server  will not send in the EHLO
                  response to a remote SMTP client.
    
           smtpd_discard_ehlo_keywords (empty)
                  A case insensitive list of EHLO keywords (pipelining,  starttls,
                  auth,  etc.)  that  the  SMTP  server  will not send in the EHLO
                  response to a remote SMTP client.
    
           smtpd_delay_open_until_valid_rcpt (yes)
                  Postpone the start of an SMTP mail  transaction  until  a  valid
                  RCPT TO command is received.
    
           Available in Postfix version 2.3 and later:
           Postfix address rewriting.
    
           receive_override_options (empty)
                  Enable or disable recipient validation, built-in content filter-
                  ing, or address mapping.
    
           Available in Postfix version 2.2 and later:
    
           local_header_rewrite_clients (permit_inet_interfaces)
                  Rewrite message header addresses in mail from these clients  and
                  update incomplete addresses with the domain name in $myorigin or
                  $mydomain; either  don't  rewrite  message  headers  from  other
                  clients at all, or rewrite message headers and update incomplete
                  addresses    with    the     domain     specified     in     the
                  remote_header_rewrite_domain parameter.
    
    
    

    AFTER QUEUE EXTERNAL CONTENT INSPECTION CONTROLS

           As  of  version  1.0,  Postfix can be configured to send new mail to an
           external content filter AFTER the mail is queued. This  content  filter
           is  expected to inject mail back into a (Postfix or other) MTA for fur-
           ther delivery. See the FILTER_README document for details.
    
           content_filter (empty)
                  The name of a mail delivery transport that filters mail after it
                  is queued.
    
    
    

    BEFORE QUEUE EXTERNAL CONTENT INSPECTION CONTROLS

           As  of  version  2.1, the Postfix SMTP server can be configured to send
           incoming mail to a real-time SMTP-based content filter BEFORE  mail  is
           queued.  This content filter is expected to inject mail back into Post-
           fix.  See the SMTPD_PROXY_README document for details on how to config-
           ure and operate this feature.
    
           smtpd_proxy_filter (empty)
                  The hostname and TCP port of the mail filtering proxy server.
    
           smtpd_proxy_ehlo ($myhostname)
                  How  the  Postfix SMTP server announces itself to the proxy fil-
                  ter.
    
           smtpd_proxy_timeout (100s)
                  The time limit for connecting to a proxy filter and for  sending
                  or receiving information.
    
    
    

    BEFORE QUEUE MILTER CONTROLS

           As of version 2.3, Postfix supports the Sendmail version 8 Milter (mail
           filter) protocol. These content filters run outside Postfix.  They  can
           inspect  the  SMTP  command  stream  and  the  message content, and can
           request modifications before mail is queued. For details see  the  MIL-
           TER_README document.
    
           smtpd_milters (empty)
                  tions.
    
           milter_macro_v ($mail_name $mail_version)
                  The {v} macro value for Milter (mail filter) applications.
    
           milter_connect_timeout (30s)
                  The time limit for connecting to a Milter (mail filter) applica-
                  tion, and for negotiating protocol options.
    
           milter_command_timeout (30s)
                  The  time  limit  for  sending an SMTP command to a Milter (mail
                  filter) application, and for receiving the response.
    
           milter_content_timeout (300s)
                  The time limit for sending message content  to  a  Milter  (mail
                  filter) application, and for receiving the response.
    
           milter_connect_macros (see 'postconf -d' output)
                  The  macros  that  are sent to Milter (mail filter) applications
                  after completion of an SMTP connection.
    
           milter_helo_macros (see 'postconf -d' output)
                  The macros that are sent to Milter  (mail  filter)  applications
                  after the SMTP HELO or EHLO command.
    
           milter_mail_macros (see 'postconf -d' output)
                  The  macros  that  are sent to Milter (mail filter) applications
                  after the SMTP MAIL FROM command.
    
           milter_rcpt_macros (see 'postconf -d' output)
                  The macros that are sent to Milter  (mail  filter)  applications
                  after the SMTP RCPT TO command.
    
           milter_data_macros (see 'postconf -d' output)
                  The  macros  that  are  sent to version 4 or higher Milter (mail
                  filter) applications after the SMTP DATA command.
    
           milter_unknown_command_macros (see 'postconf -d' output)
                  The macros that are sent to version 3  or  higher  Milter  (mail
                  filter) applications after an unknown SMTP command.
    
           milter_end_of_header_macros (see 'postconf -d' output)
                  The  macros  that  are sent to Milter (mail filter) applications
                  after the end of the message header.
    
           milter_end_of_data_macros (see 'postconf -d' output)
                  The macros that are sent to Milter  (mail  filter)  applications
                  after the message end-of-data.
    
    
    

    GENERAL CONTENT INSPECTION CONTROLS

           The  following parameters are applicable for both built-in and external
           content filters.
                  What SMTP clients are allowed to use the XFORWARD feature.
    
    
    

    SASL AUTHENTICATION CONTROLS

           Postfix SASL support (RFC 4954) can be used to authenticate remote SMTP
           clients  to  the  Postfix  SMTP server, and to authenticate the Postfix
           SMTP client to a remote SMTP server.  See the SASL_README document  for
           details.
    
           broken_sasl_auth_clients (no)
                  Enable  inter-operability  with  SMTP  clients that implement an
                  obsolete version of the AUTH command (RFC 4954).
    
           smtpd_sasl_auth_enable (no)
                  Enable SASL authentication in the Postfix SMTP server.
    
           smtpd_sasl_local_domain (empty)
                  The name of the Postfix SMTP server's local SASL  authentication
                  realm.
    
           smtpd_sasl_security_options (noanonymous)
                  Postfix SMTP server SASL security options; as of Postfix 2.3 the
                  list of available features depends on the SASL server  implemen-
                  tation that is selected with smtpd_sasl_type.
    
           smtpd_sender_login_maps (empty)
                  Optional  lookup table with the SASL login names that own sender
                  (MAIL FROM) addresses.
    
           Available in Postfix version 2.1 and later:
    
           smtpd_sasl_exceptions_networks (empty)
                  What remote SMTP clients the Postfix SMTP server will not  offer
                  AUTH support to.
    
           Available in Postfix version 2.1 and 2.2:
    
           smtpd_sasl_application_name (smtpd)
                  The  application name that the Postfix SMTP server uses for SASL
                  server initialization.
    
           Available in Postfix version 2.3 and later:
    
           smtpd_sasl_authenticated_header (no)
                  Report the SASL authenticated user name in the smtpd(8) Received
                  message header.
    
           smtpd_sasl_path (smtpd)
                  Implementation-specific information that the Postfix SMTP server
                  passes through  to  the  SASL  plug-in  implementation  that  is
                  selected with smtpd_sasl_type.
    
           smtpd_sasl_type (cyrus)
                  The SMTP TLS security level for the Postfix SMTP server; when  a
                  non-empty value is specified, this overrides the obsolete param-
                  eters smtpd_use_tls and smtpd_enforce_tls.
    
           smtpd_sasl_tls_security_options ($smtpd_sasl_security_options)
                  The SASL authentication security options that the  Postfix  SMTP
                  server uses for TLS encrypted SMTP sessions.
    
           smtpd_starttls_timeout (300s)
                  The time limit for Postfix SMTP server write and read operations
                  during TLS startup and shutdown handshake procedures.
    
           smtpd_tls_CAfile (empty)
                  A file containing (PEM  format)  CA  certificates  of  root  CAs
                  trusted to sign either remote SMTP client certificates or inter-
                  mediate CA certificates.
    
           smtpd_tls_CApath (empty)
                  A directory containing (PEM format) CA certificates of root  CAs
                  trusted to sign either remote SMTP client certificates or inter-
                  mediate CA certificates.
    
           smtpd_tls_always_issue_session_ids (yes)
                  Force the Postfix SMTP server to issue a TLS  session  id,  even
                  when   TLS   session   caching  is  turned  off  (smtpd_tls_ses-
                  sion_cache_database is empty).
    
           smtpd_tls_ask_ccert (no)
                  Ask a remote SMTP client for a client certificate.
    
           smtpd_tls_auth_only (no)
                  When TLS encryption is optional in the Postfix SMTP  server,  do
                  not announce or accept SASL authentication over unencrypted con-
                  nections.
    
           smtpd_tls_ccert_verifydepth (9)
                  The verification depth for remote SMTP client certificates.
    
           smtpd_tls_cert_file (empty)
                  File with the Postfix SMTP server RSA certificate in PEM format.
    
           smtpd_tls_exclude_ciphers (empty)
                  List  of ciphers or cipher types to exclude from the SMTP server
                  cipher list at all TLS security levels.
    
           smtpd_tls_dcert_file (empty)
                  File with the Postfix SMTP server DSA certificate in PEM format.
    
           smtpd_tls_dh1024_param_file (empty)
                  File  with DH parameters that the Postfix SMTP server should use
                  with EDH ciphers.
    
                  The  minimum  TLS cipher grade that the Postfix SMTP server will
                  use with mandatory TLS encryption.
    
           smtpd_tls_mandatory_exclude_ciphers (empty)
                  Additional list of ciphers or cipher types to exclude  from  the
                  SMTP server cipher list at mandatory TLS security levels.
    
           smtpd_tls_mandatory_protocols (SSLv3, TLSv1)
                  The  SSL/TLS  protocols accepted by the Postfix SMTP server with
                  mandatory TLS encryption.
    
           smtpd_tls_received_header (no)
                  Request that the Postfix SMTP server produces Received:  message
                  headers  that  include information about the protocol and cipher
                  used, as well as the client CommonName  and  client  certificate
                  issuer CommonName.
    
           smtpd_tls_req_ccert (no)
                  With  mandatory  TLS  encryption,  require a trusted remote SMTP
                  client certificate in order to allow TLS connections to proceed.
    
           smtpd_tls_session_cache_database (empty)
                  Name of the file containing the optional Postfix SMTP server TLS
                  session cache.
    
           smtpd_tls_session_cache_timeout (3600s)
                  The expiration time of Postfix SMTP  server  TLS  session  cache
                  information.
    
           smtpd_tls_wrappermode (no)
                  Run  the Postfix SMTP server in the non-standard "wrapper" mode,
                  instead of using the STARTTLS command.
    
           tls_daemon_random_bytes (32)
                  The number of pseudo-random bytes that an  smtp(8)  or  smtpd(8)
                  process  requests from the tlsmgr(8) server in order to seed its
                  internal pseudo random number generator (PRNG).
    
           tls_high_cipherlist (ALL:!EXPORT:!LOW:!MEDIUM:+RC4:@STRENGTH)
                  The OpenSSL cipherlist for "HIGH" grade ciphers.
    
           tls_medium_cipherlist (ALL:!EXPORT:!LOW:+RC4:@STRENGTH)
                  The OpenSSL cipherlist for "MEDIUM" or higher grade ciphers.
    
           tls_low_cipherlist (ALL:!EXPORT:+RC4:@STRENGTH)
                  The OpenSSL cipherlist for "LOW" or higher grade ciphers.
    
           tls_export_cipherlist (ALL:+RC4:@STRENGTH)
                  The OpenSSL cipherlist for "EXPORT" or higher grade ciphers.
    
           tls_null_cipherlist (eNULL:!aNULL)
                  The OpenSSL cipherlist for "NULL"  grade  ciphers  that  provide
    
           smtpd_tls_ciphers (export)
                  The minimum TLS cipher grade that the Postfix SMTP  server  will
                  use with opportunistic TLS encryption.
    
           smtpd_tls_eccert_file (empty)
                  File  with the Postfix SMTP server ECDSA certificate in PEM for-
                  mat.
    
           smtpd_tls_eckey_file ($smtpd_tls_eccert_file)
                  File with the Postfix SMTP server ECDSA private key in PEM  for-
                  mat.
    
           smtpd_tls_eecdh_grade (see 'postconf -d' output)
                  The  Postfix  SMTP server security grade for ephemeral elliptic-
                  curve Diffie-Hellman (EECDH) key exchange.
    
           tls_eecdh_strong_curve (prime256v1)
                  The elliptic curve used by the SMTP server for  sensibly  strong
                  ephemeral ECDH key exchange.
    
           tls_eecdh_ultra_curve (secp384r1)
                  The  elliptic curve used by the SMTP server for maximally strong
                  ephemeral ECDH key exchange.
    
    
    

    OBSOLETE STARTTLS CONTROLS

           The following configuration parameters  exist  for  compatibility  with
           Postfix  versions  before  2.3.  Support for these will be removed in a
           future release.
    
           smtpd_use_tls (no)
                  Opportunistic TLS: announce STARTTLS support  to  SMTP  clients,
                  but do not require that clients use TLS encryption.
    
           smtpd_enforce_tls (no)
                  Mandatory  TLS:  announce  STARTTLS support to SMTP clients, and
                  require that clients use TLS encryption.
    
           smtpd_tls_cipherlist (empty)
                  Obsolete Postfix < 2.3 control for the Postfix SMTP  server  TLS
                  cipher list.
    
    
    

    VERP SUPPORT CONTROLS

           With  VERP  style delivery, each recipient of a message receives a cus-
           tomized copy of the message with his/her own recipient address  encoded
           in the envelope sender address.  The VERP_README file describes config-
           uration and operation details of Postfix support for variable  envelope
           return  path addresses.  VERP style delivery is requested with the SMTP
           XVERP command or with the "sendmail  -V"  command-line  option  and  is
           available in Postfix version 1.1 and later.
    
           default_verp_delimiters (+=)
                  What SMTP clients are allowed to specify the XVERP command.
    
    
    

    TROUBLE SHOOTING CONTROLS

           The DEBUG_README document describes how to debug parts of  the  Postfix
           mail  system.  The  methods  vary from making the software log a lot of
           detail, to running some daemon processes under control of a call tracer
           or debugger.
    
           debug_peer_level (2)
                  The  increment  in verbose logging level when a remote client or
                  server matches a pattern in the debug_peer_list parameter.
    
           debug_peer_list (empty)
                  Optional list of remote client or  server  hostname  or  network
                  address  patterns  that  cause  the  verbose  logging  level  to
                  increase by the amount specified in $debug_peer_level.
    
           error_notice_recipient (postmaster)
                  The recipient of postmaster notifications  about  mail  delivery
                  problems that are caused by policy, resource, software or proto-
                  col errors.
    
           internal_mail_filter_classes (empty)
                  What categories of Postfix-generated mail are subject to before-
                  queue content inspection by non_smtpd_milters, header_checks and
                  body_checks.
    
           notify_classes (resource, software)
                  The list of error classes that are reported to the postmaster.
    
           soft_bounce (no)
                  Safety net to keep mail queued that would otherwise be  returned
                  to the sender.
    
           Available in Postfix version 2.1 and later:
    
           smtpd_authorized_xclient_hosts (empty)
                  What SMTP clients are allowed to use the XCLIENT feature.
    
    
    

    KNOWN VERSUS UNKNOWN RECIPIENT CONTROLS

           As  of  Postfix  version  2.0, the SMTP server rejects mail for unknown
           recipients. This prevents the mail queue from clogging up with undeliv-
           erable  MAILER-DAEMON messages. Additional information on this topic is
           in the LOCAL_RECIPIENT_README and ADDRESS_CLASS_README documents.
    
           show_user_unknown_table_name (yes)
                  Display the name of the recipient table in  the  "User  unknown"
                  responses.
    
           canonical_maps (empty)
                  Optional  address  mapping lookup tables for message headers and
                  envelopes.
    
           proxy_interfaces (empty)
                  The  network  interface addresses that this mail system receives
                  mail on by way of a proxy or network address translation unit.
    
           inet_protocols (ipv4)
                  The Internet protocols Postfix will attempt to use  when  making
                  or accepting connections.
    
           local_recipient_maps (proxy:unix:passwd.byname $alias_maps)
                  Lookup tables with all names or addresses of local recipients: a
                  recipient   address   is   local   when   its   domain   matches
                  $mydestination, $inet_interfaces or $proxy_interfaces.
    
           unknown_local_recipient_reject_code (550)
                  The numerical Postfix SMTP server response code when a recipient
                  address is local, and $local_recipient_maps specifies a list  of
                  lookup tables that does not match the recipient.
    
           Parameters concerning known/unknown recipients of relay destinations:
    
           relay_domains ($mydestination)
                  What  destination  domains  (and subdomains thereof) this system
                  will relay mail to.
    
           relay_recipient_maps (empty)
                  Optional lookup tables with all valid addresses in  the  domains
                  that match $relay_domains.
    
           unknown_relay_recipient_reject_code (550)
                  The  numerical  Postfix  SMTP server reply code when a recipient
                  address matches $relay_domains, and relay_recipient_maps  speci-
                  fies  a  list of lookup tables that does not match the recipient
                  address.
    
           Parameters  concerning  known/unknown  recipients  in   virtual   alias
           domains:
    
           virtual_alias_domains ($virtual_alias_maps)
                  Postfix  is  final destination for the specified list of virtual
                  alias domains, that is, domains  for  which  all  addresses  are
                  aliased to addresses in other local or remote domains.
    
           virtual_alias_maps ($virtual_maps)
                  Optional  lookup  tables  that  alias specific mail addresses or
                  domains to other local or remote address.
    
           unknown_virtual_alias_reject_code (550)
                  The SMTP server reply code  when  a  recipient  address  matches
                  $virtual_alias_domains, and $virtual_alias_maps specifies a list
                  of lookup tables that does not match the recipient address.
    
                  $virtual_mailbox_domains,  and $virtual_mailbox_maps specifies a
                  list of lookup tables that does not match the recipient address.
    
    
    

    RESOURCE AND RATE CONTROLS

           The following parameters limit resource usage by the SMTP server and/or
           control client request rates.
    
           line_length_limit (2048)
                  Upon input, long lines are chopped up into  pieces  of  at  most
                  this length; upon delivery, long lines are reconstructed.
    
           queue_minfree (0)
                  The minimal amount of free space in bytes in the queue file sys-
                  tem that is needed to receive mail.
    
           message_size_limit (10240000)
                  The maximal size in  bytes  of  a  message,  including  envelope
                  information.
    
           smtpd_recipient_limit (1000)
                  The  maximal  number  of recipients that the Postfix SMTP server
                  accepts per message delivery request.
    
           smtpd_timeout (normal: 300s, stress: 10s)
                  The time limit for sending a Postfix SMTP  server  response  and
                  for receiving a remote SMTP client request.
    
           smtpd_history_flush_threshold (100)
                  The  maximal  number of lines in the Postfix SMTP server command
                  history before it is flushed upon receipt of EHLO, RSET, or  end
                  of DATA.
    
           Available in Postfix version 2.3 and later:
    
           smtpd_peername_lookup (yes)
                  Attempt  to  look up the remote SMTP client hostname, and verify
                  that the name matches the client IP address.
    
           The per SMTP client connection count and request rate limits are imple-
           mented  in co-operation with the anvil(8) service, and are available in
           Postfix version 2.2 and later.
    
           smtpd_client_connection_count_limit (50)
                  How many simultaneous connections any client is allowed to  make
                  to this service.
    
           smtpd_client_connection_rate_limit (0)
                  The  maximal number of connection attempts any client is allowed
                  to make to this service per time unit.
    
           smtpd_client_message_rate_limit (0)
                  The maximal number of message delivery requests that any  client
    
           smtpd_client_new_tls_session_rate_limit (0)
                  The  maximal  number of new (i.e., uncached) TLS sessions that a
                  remote SMTP client is allowed to negotiate with this service per
                  time unit.
    
    
    

    TARPIT CONTROLS

           When  a  remote  SMTP  client makes errors, the Postfix SMTP server can
           insert delays before responding. This can help to  slow  down  run-away
           software.   The  behavior is controlled by an error counter that counts
           the number of errors within an SMTP session that a client makes without
           delivering mail.
    
           smtpd_error_sleep_time (1s)
                  With  Postfix  version  2.1  and later: the SMTP server response
                  delay after a client has made more than  $smtpd_soft_error_limit
                  errors,  and  fewer than $smtpd_hard_error_limit errors, without
                  delivering mail.
    
           smtpd_soft_error_limit (10)
                  The number of errors a remote SMTP client  is  allowed  to  make
                  without  delivering  mail  before  the Postfix SMTP server slows
                  down all its responses.
    
           smtpd_hard_error_limit (normal: 20, stress: 1)
                  The maximal number of errors a remote SMTP client is allowed  to
                  make without delivering mail.
    
           smtpd_junk_command_limit (normal: 100, stress: 1)
                  The  number  of  junk commands (NOOP, VRFY, ETRN or RSET) that a
                  remote SMTP client can  send  before  the  Postfix  SMTP  server
                  starts to increment the error counter with each junk command.
    
           Available in Postfix version 2.1 and later:
    
           smtpd_recipient_overshoot_limit (1000)
                  The  number  of recipients that a remote SMTP client can send in
                  excess  of  the  limit  specified  with  $smtpd_recipient_limit,
                  before  the Postfix SMTP server increments the per-session error
                  count for each excess recipient.
    
    
    

    ACCESS POLICY DELEGATION CONTROLS

           As of version 2.1, Postfix can be configured to delegate access  policy
           decisions  to  an  external  server that runs outside Postfix.  See the
           file SMTPD_POLICY_README for more information.
    
           smtpd_policy_service_max_idle (300s)
                  The time after which an idle SMTPD policy service connection  is
                  closed.
    
           smtpd_policy_service_max_ttl (1000s)
                  The  time  after which an active SMTPD policy service connection
                  is closed.
                  $smtpd_helo_restrictions.
    
           parent_domain_matches_subdomains (see 'postconf -d' output)
                  What Postfix features match subdomains of "domain.tld" automati-
                  cally, instead of requiring an explicit ".domain.tld" pattern.
    
           smtpd_client_restrictions (empty)
                  Optional  SMTP  server  access  restrictions in the context of a
                  client SMTP connection request.
    
           smtpd_helo_required (no)
                  Require that a remote  SMTP  client  introduces  itself  at  the
                  beginning of an SMTP session with the HELO or EHLO command.
    
           smtpd_helo_restrictions (empty)
                  Optional  restrictions  that  the Postfix SMTP server applies in
                  the context of the SMTP HELO command.
    
           smtpd_sender_restrictions (empty)
                  Optional restrictions that the Postfix SMTP  server  applies  in
                  the context of the MAIL FROM command.
    
           smtpd_recipient_restrictions (permit_mynetworks, reject_unauth_destina-
           tion)
                  The  access restrictions that the Postfix SMTP server applies in
                  the context of the RCPT TO command.
    
           smtpd_etrn_restrictions (empty)
                  Optional SMTP server access restrictions in  the  context  of  a
                  client ETRN request.
    
           allow_untrusted_routing (no)
                  Forward       mail       with      sender-specified      routing
                  (user[@%!]remote[@%!]site)    from    untrusted    clients    to
                  destinations matching $relay_domains.
    
           smtpd_restriction_classes (empty)
                  User-defined aliases for groups of access restrictions.
    
           smtpd_null_access_lookup_key (<>)
                  The  lookup  key  to be used in SMTP access(5) tables instead of
                  the null sender address.
    
           permit_mx_backup_networks (empty)
                  Restrict the use of the permit_mx_backup SMTP access feature  to
                  only domains whose primary MX hosts match the listed networks.
    
           Available in Postfix version 2.0 and later:
    
           smtpd_data_restrictions (empty)
                  Optional  access  restrictions  that  the  Postfix  SMTP  server
                  applies in the context of the SMTP DATA command.
                  recipient     addresses,     even     when      no      explicit
                  reject_unlisted_recipient access restriction is specified.
    
           Available in Postfix version 2.2 and later:
    
           smtpd_end_of_data_restrictions (empty)
                  Optional  access  restrictions  that  the  Postfix  SMTP  server
                  applies in the context of the SMTP END-OF-DATA command.
    
    
    

    SENDER AND RECIPIENT ADDRESS VERIFICATION CONTROLS

           Postfix version 2.1 introduces sender and recipient  address  verifica-
           tion.  This feature is implemented by sending probe email messages that
           are  not  actually  delivered.   This  feature  is  requested  via  the
           reject_unverified_sender    and    reject_unverified_recipient   access
           restrictions.  The status of verification probes is maintained  by  the
           verify(8)  server.  See the file ADDRESS_VERIFICATION_README for infor-
           mation about how to configure and operate the Postfix  sender/recipient
           address verification service.
    
           address_verify_poll_count (3)
                  How many times to query the verify(8) service for the completion
                  of an address verification request in progress.
    
           address_verify_poll_delay (3s)
                  The delay between queries for the completion of an address veri-
                  fication request in progress.
    
           address_verify_sender ($double_bounce_sender)
                  The  sender address to use in address verification probes; prior
                  to Postfix 2.5 the default was "postmaster".
    
           unverified_sender_reject_code (450)
                  The numerical Postfix SMTP server response code when a recipient
                  address is rejected by the reject_unverified_sender restriction.
    
           unverified_recipient_reject_code (450)
                  The numerical Postfix SMTP  server  response  when  a  recipient
                  address  is rejected by the reject_unverified_recipient restric-
                  tion.
    
           Available in Postfix version 2.6 and later:
    
           unverified_sender_defer_code (450)
                  The numerical Postfix SMTP server response code  when  a  sender
                  address probe fails due to a temporary error condition.
    
           unverified_recipient_defer_code (450)
                  The  numerical  Postfix  SMTP  server  response when a recipient
                  address probe fails due to a temporary error condition.
    
           unverified_sender_reject_reason (empty)
                  The  Postfix  SMTP  server's  reply  when  rejecting  mail  with
    
    
    

    ACCESS CONTROL RESPONSES

           The following parameters control numerical SMTP reply codes and/or text
           responses.
    
           access_map_reject_code (554)
                  The numerical Postfix SMTP server response code for an access(5)
                  map "reject" action.
    
           defer_code (450)
                  The numerical Postfix SMTP server response code  when  a  remote
                  SMTP client request is rejected by the "defer" restriction.
    
           invalid_hostname_reject_code (501)
                  The  numerical Postfix SMTP server response code when the client
                  HELO  or   EHLO   command   parameter   is   rejected   by   the
                  reject_invalid_helo_hostname restriction.
    
           maps_rbl_reject_code (554)
                  The  numerical  Postfix  SMTP server response code when a remote
                  SMTP  client  request  is  blocked  by  the   reject_rbl_client,
                  reject_rhsbl_client, reject_rhsbl_sender or reject_rhsbl_recipi-
                  ent restriction.
    
           non_fqdn_reject_code (504)
                  The numerical Postfix SMTP  server  reply  code  when  a  client
                  request   is   rejected  by  the  reject_non_fqdn_helo_hostname,
                  reject_non_fqdn_sender or reject_non_fqdn_recipient restriction.
    
           plaintext_reject_code (450)
                  The  numerical  Postfix SMTP server response code when a request
                  is rejected by the reject_plaintext_session restriction.
    
           reject_code (554)
                  The numerical Postfix SMTP server response code  when  a  remote
                  SMTP client request is rejected by the "reject" restriction.
    
           relay_domains_reject_code (554)
                  The  numerical  Postfix  SMTP server response code when a client
                  request is rejected by the  reject_unauth_destination  recipient
                  restriction.
    
           unknown_address_reject_code (450)
                  The numerical Postfix SMTP server response code when a sender or
                  recipient      address      is       rejected       by       the
                  reject_unknown_sender_domain  or reject_unknown_recipient_domain
                  restriction.
    
           unknown_client_reject_code (450)
                  The numerical Postfix SMTP server response code  when  a  client
                  without  valid  address  <=>  name  mapping  is  rejected by the
                  reject_unknown_client_hostname restriction.
    
                  ent_bounce restriction.
    
           rbl_reply_maps (empty)
                  Optional lookup tables with RBL response templates.
    
           Available in Postfix version 2.6 and later:
    
           access_map_defer_code (450)
                  The numerical Postfix SMTP server response code for an access(5)
                  map   "defer"    action,    including    "defer_if_permit"    or
                  "defer_if_reject".
    
           reject_tempfail_action (defer_if_permit)
                  The  Postfix SMTP server's action when a reject-type restriction
                  fails due to a temporary error condition.
    
           unknown_helo_hostname_tempfail_action ($reject_tempfail_action)
                  The Postfix SMTP server's action when  reject_unknown_helo_host-
                  name fails due to an temporary error condition.
    
           unknown_address_tempfail_action ($reject_tempfail_action)
                  The       Postfix       SMTP      server's      action      when
                  reject_unknown_sender_domain or  reject_unknown_recipient_domain
                  fail due to a temporary error condition.
    
    
    

    MISCELLANEOUS CONTROLS

           config_directory (see 'postconf -d' output)
                  The  default  location of the Postfix main.cf and master.cf con-
                  figuration files.
    
           daemon_timeout (18000s)
                  How much time a Postfix daemon process  may  take  to  handle  a
                  request before it is terminated by a built-in watchdog timer.
    
           command_directory (see 'postconf -d' output)
                  The location of all postfix administrative commands.
    
           double_bounce_sender (double-bounce)
                  The  sender  address of postmaster notifications that are gener-
                  ated by the mail system.
    
           ipc_timeout (3600s)
                  The time limit for sending  or  receiving  information  over  an
                  internal communication channel.
    
           mail_name (Postfix)
                  The  mail system name that is displayed in Received: headers, in
                  the SMTP greeting banner, and in bounced mail.
    
           mail_owner (postfix)
                  The UNIX system account that owns the  Postfix  queue  and  most
                  Postfix daemon processes.
                  than "strangers".
    
           myorigin ($myhostname)
                  The  domain  name that locally-posted mail appears to come from,
                  and that locally posted mail is delivered to.
    
           process_id (read-only)
                  The process ID of a Postfix command or daemon process.
    
           process_name (read-only)
                  The process name of a Postfix command or daemon process.
    
           queue_directory (see 'postconf -d' output)
                  The location of the Postfix top-level queue directory.
    
           recipient_delimiter (empty)
                  The  separator  between  user  names  and   address   extensions
                  (user+foo).
    
           smtpd_banner ($myhostname ESMTP $mail_name)
                  The  text  that follows the 220 status code in the SMTP greeting
                  banner.
    
           syslog_facility (mail)
                  The syslog facility of Postfix logging.
    
           syslog_name (see 'postconf -d' output)
                  The mail system name that is prepended to the  process  name  in
                  syslog  records,  so  that  "smtpd" becomes, for example, "post-
                  fix/smtpd".
    
           Available in Postfix version 2.2 and later:
    
           smtpd_forbidden_commands (CONNECT, GET, POST)
                  List of commands that causes the Postfix SMTP server to  immedi-
                  ately terminate the session with a 221 code.
    
           Available in Postfix version 2.5 and later:
    
           smtpd_client_port_logging (no)
                  Enable logging of the remote SMTP client port in addition to the
                  hostname and IP address.
    
    
    

    SEE ALSO

           anvil(8), connection/rate limiting
           cleanup(8), message canonicalization
           tlsmgr(8), TLS session and PRNG management
           trivial-rewrite(8), address resolver
           verify(8), address verification service
           postconf(5), configuration parameters
           master(5), generic daemon options
           master(8), process manager
           TLS_README, Postfix STARTTLS howto
           VERP_README, Postfix XVERP extension
           XCLIENT_README, Postfix XCLIENT extension
           XFORWARD_README, Postfix XFORWARD extension
    
    
    

    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
    
           SASL support originally by:
           Till Franke
           SuSE Rhein/Main AG
           65760 Eschborn, Germany
    
           TLS support originally by:
           Lutz Jaenicke
           BTU Cottbus
           Allgemeine Elektrotechnik
           Universitaetsplatz 3-4
           D-03044 Cottbus, Germany
    
           Revised TLS support by:
           Victor Duchovni
           Morgan Stanley
    
                                                                          SMTPD(8)
    
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