SMTPD(8)		    System Manager's Manual		      SMTPD(8)



NAME
       smtpd - Postfix SMTP server

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
       of other trouble.

CONFIGURATION PARAMETERS
       Changes to main.cf are picked up automatically, as  smtpd(8)  processes
       run for only a limited amount of time. Use the command "postfix reload"
       to speed up a change.

       The text below provides only a parameter summary. See  postconf(5)  for
       more details including examples.

COMPATIBILITY CONTROLS
       The  following  parameters  work	 around implementation errors in other
       software, and/or allow you to override standards in  order  to  prevent
       undesirable use.

       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:

       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).

       Available in Postfix version 2.6 and later:

       tcp_windowsize (0)
	      An  optional  workaround for routers that break TCP window scal-
	      ing.

ADDRESS REWRITING CONTROLS
       See the ADDRESS_REWRITING_README document for a detailed discussion  of
       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_re-
	      write_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)
	      A	 list  of  Milter (mail filter) applications for new mail that
	      arrives via the Postfix smtpd(8) server.

       milter_protocol (6)
	      The mail filter protocol version and  optional  protocol	exten-
	      sions  for  communication	 with  a  Milter application; prior to
	      Postfix 2.6 the default protocol is 2.

       milter_default_action (tempfail)
	      The default action when a Milter (mail  filter)  application  is
	      unavailable or mis-configured.

       milter_macro_daemon_name ($myhostname)
	      The  {daemon_name} macro value for Milter (mail filter) applica-
	      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.

       Available in Postfix version 2.1 and later:

       receive_override_options (empty)
	      Enable or disable recipient validation, built-in content filter-
	      ing, or address mapping.

EXTERNAL CONTENT INSPECTION CONTROLS
       The  following  parameters  are	applicable  for	 both before-queue and
       after-queue content filtering.

       Available in Postfix version 2.1 and later:

       smtpd_authorized_xforward_hosts (empty)
	      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  SASL	 plug-in  type that the Postfix SMTP server should use
	      for authentication.

       Available in Postfix version 2.5 and later:

       cyrus_sasl_config_path (empty)
	      Search path for Cyrus SASL application configuration files, cur-
	      rently used only to locate the $smtpd_sasl_path.conf file.

STARTTLS SUPPORT CONTROLS
       Detailed	 information  about STARTTLS configuration may be found in the
       TLS_README document.

       smtpd_tls_security_level (empty)
	      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.

       smtpd_tls_dh512_param_file (empty)
	      File with DH parameters that the Postfix SMTP server should  use
	      with EDH ciphers.

       smtpd_tls_dkey_file ($smtpd_tls_dcert_file)
	      File with the Postfix SMTP server DSA private key in PEM format.

       smtpd_tls_key_file ($smtpd_tls_cert_file)
	      File with the Postfix SMTP server RSA private key in PEM format.

       smtpd_tls_loglevel (0)
	      Enable additional Postfix SMTP server logging of TLS activity.

       smtpd_tls_mandatory_ciphers (medium)
	      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
	      authentication without encryption.

       Available in Postfix version 2.5 and later:

       smtpd_tls_fingerprint_digest (md5)
	      The message digest algorithm used to  construct  client-certifi-
	      cate    fingerprints    for    check_ccert_access	   and	  per-
	      mit_tls_clientcerts.

       Available in Postfix version 2.6 and later:

       smtpd_tls_protocols (empty)
	      List of TLS protocols that the Postfix SMTP server will  exclude
	      or include with opportunistic TLS encryption.

       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 (+=)
	      The two default VERP delimiter characters.

       verp_delimiter_filter (-=+)
	      The characters Postfix accepts as VERP delimiter	characters  on
	      the Postfix sendmail(1) command line and in SMTP commands.

       Available in Postfix version 1.1 and 2.0:

       authorized_verp_clients ($mynetworks)
	      What SMTP clients are allowed to specify the XVERP command.

       Available in Postfix version 2.1 and later:

       smtpd_authorized_verp_clients ($authorized_verp_clients)
	      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.

       recipient_canonical_maps (empty)
	      Optional	address	 mapping lookup tables for envelope and header
	      recipient addresses.

       Parameters concerning known/unknown local recipients:

       mydestination ($myhostname, localhost.$mydomain, localhost)
	      The list of domains that are delivered via the  $local_transport
	      mail delivery transport.

       inet_interfaces (all)
	      The  network  interface addresses that this mail system receives
	      mail on.

       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 $mydestina-
	      tion, $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.

       Parameters  concerning  known/unknown  recipients  in  virtual  mailbox
       domains:

       virtual_mailbox_domains ($virtual_mailbox_maps)
	      Postfix is final destination for the specified list of  domains;
	      mail  is	delivered  via	the  $virtual_transport	 mail delivery
	      transport.

       virtual_mailbox_maps (empty)
	      Optional lookup tables with all valid addresses in  the  domains
	      that match $virtual_mailbox_domains.

       unknown_virtual_mailbox_reject_code (550)
	      The  SMTP	 server	 reply	code  when a recipient address matches
	      $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
	      is  allowed to make to this service per time unit, regardless of
	      whether or not Postfix actually accepts those messages.

       smtpd_client_recipient_rate_limit (0)
	      The maximal number of recipient addresses	 that  any  client  is
	      allowed  to  send	 to  this service per time unit, regardless of
	      whether or not Postfix actually accepts those recipients.

       smtpd_client_event_limit_exceptions ($mynetworks)
	      Clients that are	excluded  from	connection  count,  connection
	      rate, or SMTP request rate restrictions.

       Available in Postfix version 2.3 and later:

       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_policy_service_timeout (100s)
	      The time limit for connecting to, writing to or receiving from a
	      delegated SMTPD policy server.

ACCESS CONTROLS
       The  SMTPD_ACCESS_README document gives an introduction to all the SMTP
       server access control features.

       smtpd_delay_reject (yes)
	      Wait   until   the   RCPT	  TO   command	  before    evaluating
	      $smtpd_client_restrictions,     $smtpd_helo_restrictions	   and
	      $smtpd_sender_restrictions,  or  wait  until  the	 ETRN  command
	      before	   evaluating	   $smtpd_client_restrictions	   and
	      $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 destina-
	      tions 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.

       smtpd_expansion_filter (see 'postconf -d' output)
	      What  characters	are  allowed  in $name expansions of RBL reply
	      templates.

       Available in Postfix version 2.1 and later:

       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_reject_unlisted_recipient (yes)
	      Request that the Postfix SMTP server rejects  mail  for  unknown
	      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
	      reject_unverified_sender.

       unverified_recipient_reject_reason (empty)
	      The  Postfix  SMTP  server's  reply  when	 rejecting  mail  with
	      reject_unverified_recipient.

       unverified_sender_tempfail_action ($reject_tempfail_action)
	      The Postfix SMTP server's action	when  reject_unverified_sender
	      fails due to a temporary error condition.

       unverified_recipient_tempfail_action ($reject_tempfail_action)
	      The  Postfix SMTP server's action when reject_unverified_recipi-
	      ent fails due to a temporary error condition.

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.

       unknown_hostname_reject_code (450)
	      The  numerical  Postfix SMTP server response code when the host-
	      name specified with the HELO or EHLO command is rejected by  the
	      reject_unknown_helo_hostname restriction.

       Available in Postfix version 2.0 and later:

       default_rbl_reply (see 'postconf -d' output)
	      The  default SMTP server response template for a request that is
	      rejected by an RBL-based restriction.

       multi_recipient_bounce_reject_code (550)
	      The numerical Postfix SMTP server response code  when  a	remote
	      SMTP  client  request  is	 blocked  by  the reject_multi_recipi-
	      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.

       max_idle (100s)
	      The maximum amount of time that an idle Postfix  daemon  process
	      waits for an incoming connection before terminating voluntarily.

       max_use (100)
	      The maximal number of incoming connections that a Postfix daemon
	      process will service before terminating voluntarily.

       myhostname (see 'postconf -d' output)
	      The internet hostname of this mail system.

       mynetworks (see 'postconf -d' output)
	      The list of "trusted" SMTP clients  that	have  more  privileges
	      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
       syslogd(8), system logging

README FILES
       Use "postconf readme_directory" or "postconf html_directory" to	locate
       this information.
       ADDRESS_CLASS_README, blocking unknown hosted or relay recipients
       ADDRESS_REWRITING_README Postfix address manipulation
       FILTER_README, external after-queue content filter
       LOCAL_RECIPIENT_README, blocking unknown local recipients
       MILTER_README, before-queue mail filter applications
       SMTPD_ACCESS_README, built-in access policies
       SMTPD_POLICY_README, external policy server
       SMTPD_PROXY_README, external before-queue content filter
       SASL_README, Postfix SASL howto
       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)