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Linux 2.6 - man page for smtpd (linux section 8postfix)

SMTPD(8postfix) 								  SMTPD(8postfix)

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 trans-
       actions 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 program 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 parame-
       ters given to HELO, ETRN, MAIL FROM, VRFY and RCPT TO commands. They  are  detailed  below
       and in the main.cf configuration 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 Status 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 postmaster  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 lim-
       ited 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 includ-
       ing 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_session_cache_database is empty).

       Available in Postfix version 2.6 and later:

       tcp_windowsize(0)
	      An optional workaround for routers that break TCP window scaling.

       Available in Postfix version 2.7 and later:

       smtpd_command_filter (empty)
	      A mechanism to transform commands from remote SMTP clients.

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 filtering, or address map-
	      ping.

       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 mes-
	      sage 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  fil-
       ter  AFTER  the mail is queued. This content filter is expected to inject mail back into a
       (Postfix or other) MTA for further delivery. See the FILTER_README document for details.

       content_filter (empty)
	      After the message is queued, send  the  entire  message  to  the	specified  trans-
	      port:destination.

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  Postfix.   See the SMTPD_PROXY_README document for
       details on how to configure 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 filter.

       smtpd_proxy_options (empty)
	      List of options that control how	the  Postfix  SMTP  server  communicates  with	a
	      before-queue content filter.

       smtpd_proxy_timeout(100s)
	      The time limit for connecting to a proxy filter and for sending or receiving infor-
	      mation.

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 MILTER_README document.

       smtpd_milters (empty)
	      A list of Milter (mail filter) applications for new mail that arrives via the Post-
	      fix smtpd(8) server.

       milter_protocol(6)
	      The mail filter protocol version and optional protocol extensions 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) applications.

       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) application, and for  nego-
	      tiating 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 filtering, or address map-
	      ping.

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

       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  implementation  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 initializa-
	      tion.

       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, currently 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	 parameters   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 (see 'postconf -d' output)
	      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 intermediate 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 intermediate 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_session_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 connections.

       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 Com-
	      monName 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-certificate fingerprints for
	      check_ccert_access and permit_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 opportunis-
	      tic TLS encryption.

       smtpd_tls_eccert_file (empty)
	      File with the Postfix SMTP server ECDSA certificate in PEM format.

       smtpd_tls_eckey_file ($smtpd_tls_eccert_file)
	      File with the Postfix SMTP server ECDSA private key in PEM format.

       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.

       Available in Postfix version 2.8 and later:

       tls_preempt_cipherlist (no)
	      With  SSLv3  and	later,	use  the  server's cipher preference order instead of the
	      client's cipher preference order.

       tls_disable_workarounds (see 'postconf -d' output)
	      List or bit-mask of OpenSSL bug work-arounds to disable.

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 customized copy of the
       message with his/her own recipient address encoded in the envelope  sender  address.   The
       VERP_README  file  describes  configuration  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  send-
	      mail(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  pro-
       cesses 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 protocol 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.

       smtpd_reject_footer (empty)
	      Optional information that is appended after each SMTP server 4XX or 5XX response.

       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  pre-
       vents  the  mail  queue	from clogging up with undeliverable MAILER-DAEMON messages. Addi-
       tional 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 connec-
	      tions.

       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_inter-
	      faces.

       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 specifies 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 $vir-
	      tual_mailbox_domains.

       unknown_virtual_mailbox_reject_code(550)
	      The SMTP	server	reply  code  when  a  recipient  address  matches  $virtual_mail-
	      box_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 system 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, overload: 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 implemented in co-opera-
       tion 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 smtpd_client_*_count/rate_limit 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, overload: 1)
	      The maximal number of errors a remote SMTP client is allowed to make without deliv-
	      ering mail.

       smtpd_junk_command_limit (normal: 100, overload: 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  con-
       trol 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" automatically, 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 with the HELO or EHLO command
	      before sending the MAIL command or other commands that require EHLO negotiation.

       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_destination)
	      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.

       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 verification.  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 information about how to configure and  oper-
       ate the Postfix sender/recipient address verification service.

       address_verify_poll_count (normal: 3, overload: 1)
	      How many times to query the verify(8) service for the completion of an address ver-
	      ification request in progress.

       address_verify_poll_delay(3s)
	      The delay between queries for the completion of an address verification 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 restriction.

       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_recipi-
	      ent.

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

       unverified_recipient_tempfail_action ($reject_tempfail_action)
	      The Postfix SMTP server's action when reject_unverified_recipient 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 com-
	      mand 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_reverse_client, reject_rhsbl_sender or reject_rhsbl_recipient restric-
	      tion.

       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_recip-
	      ient 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 hostname specified with
	      the HELO or EHLO command is rejected by the  reject_unknown_helo_hostname  restric-
	      tion.

       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_recipient_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 tem-
	      porary error condition.

       unknown_helo_hostname_tempfail_action ($reject_tempfail_action)
	      The  Postfix SMTP server's action when reject_unknown_helo_hostname 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 configuration 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 generated by the mail  sys-
	      tem.

       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 pro-
	      cesses.

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

       max_use(100)
	      The  maximal number of incoming connections that a Postfix daemon process will ser-
	      vice 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, "postfix/smtpd".

       Available in Postfix version 2.2 and later:

       smtpd_forbidden_commands (CONNECT, GET, POST)
	      List of commands that cause the Postfix SMTP server to  immediately  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(8postfix)


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