SMTPD(8)                                                              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) dae-
       mon, 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  con-
       nection  requests, and for parameters 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 4409 (Message submission)
       RFC 4954 (AUTH command)
       RFC 5321 (SMTP protocol)

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 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 remote  SMTP  clients
              that implement an obsolete version of the AUTH com-
              mand (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  com-
              ments 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  key-
              words  (pipelining,  starttls, auth, etc.) that the
              Postfix 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 (pipelin-
              ing, starttls, auth, etc.) that  the  Postfix  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 ses-
              sion 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.

       Available in Postfix version 2.9 and later:

       smtpd_per_record_deadline (normal: no, overload: yes)
              Change  the  behavior  of  the  smtpd_timeout  time
              limit, from a time limit per read or  write  system
              call, to a time limit to send or receive a complete
              record (an SMTP command line, SMTP  response  line,
              SMTP  message  content  line,  or TLS protocol mes-
              sage).

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 mapping.

       Available in Postfix version 2.2 and later:

       local_header_rewrite_clients (permit_inet_interfaces)
              Rewrite message header addresses in mail from these
              clients  and  update  incomplete addresses with the
              domain name in $myorigin or $mydomain; either don't
              rewrite  message headers from other clients at all,
              or rewrite message headers  and  update  incomplete
              addresses   with   the   domain  specified  in  the
              remote_header_rewrite_domain parameter.

BEFORE-SMTPD PROXY AGENT
       Available in Postfix version 2.10 and later:

       smtpd_upstream_proxy_protocol (empty)
              The name of the proxy protocol used by an  optional
              before-smtpd proxy agent.

       smtpd_upstream_proxy_timeout (5s)
              The  time  limit  for  the proxy protocol specified
              with the smtpd_upstream_proxy_protocol 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 further delivery.
       See the FILTER_README document for details.

       content_filter (empty)
              After the message is queued, send the  entire  mes-
              sage to the specified transport:destination.

BEFORE QUEUE EXTERNAL CONTENT INSPECTION CONTROLS
       As  of version 2.1, the Postfix SMTP server can be config-
       ured to send incoming mail to a real-time SMTP-based  con-
       tent 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 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 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 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 MILTER_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  pro-
              tocol  extensions  for  communication with a Milter
              application; prior to Postfix 2.6 the default  pro-
              tocol 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 fil-
              ter) applications.

       milter_macro_v ($mail_name $mail_version)
              The {v} macro value for Milter (mail filter) appli-
              cations.

       milter_connect_timeout (30s)
              The time limit for connecting  to  a  Milter  (mail
              filter)  application,  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 connec-
              tion.

       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 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 remote SMTP clients are  allowed  to  use  the
              XFORWARD feature.

SASL AUTHENTICATION CONTROLS
       Postfix  SASL  support (RFC 4954) can be used to authenti-
       cate 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 remote  SMTP  clients
              that implement an obsolete version of the AUTH com-
              mand (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 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 Post-
              fix 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 configura-
              tion 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_secu-
       rity_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 certifi-
              cates.

       smtpd_tls_always_issue_session_ids (yes)
              Force the Postfix SMTP server to issue a  TLS  ses-
              sion  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  authentica-
              tion over unencrypted connections.

       smtpd_tls_ccert_verifydepth (9)
              The  verification depth for remote SMTP client cer-
              tificates.

       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 Postfix SMTP server cipher list at
              mandatory TLS security levels.

       smtpd_tls_mandatory_protocols (!SSLv2)
              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
              remote SMTP client CommonName and  client  certifi-
              cate 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 ses-
              sion cache information.

       smtpd_tls_wrappermode (no)
              Run  the  Postfix  SMTP  server in the non-standard
              "wrapper" mode, instead of using the STARTTLS  com-
              mand.

       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  to  construct  remote
              SMTP  client-certificate fingerprints or public key
              fingerprints   (Postfix   2.9   and   later)    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 opportunistic 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 Postfix SMTP server
              for sensibly strong ephemeral ECDH key exchange.

       tls_eecdh_ultra_curve (secp384r1)
              The elliptic curve used by the Postfix 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 Postfix SMTP server's
              cipher  preference  order  instead  of  the  remote
              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  compati-
       bility 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
              remote  SMTP  clients,  but  do  not  require  that
              clients use TLS encryption.

       smtpd_enforce_tls (no)
              Mandatory TLS: announce STARTTLS support to  remote
              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 sendmail(1) command  line
              and in SMTP commands.

       Available in Postfix version 1.1 and 2.0:

       authorized_verp_clients ($mynetworks)
              What remote 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 remote 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 sub-
              ject  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
              Postfix 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 remote SMTP clients are  allowed  to  use  the
              XCLIENT feature.

       Available in Postfix version 2.10 and later:

       smtpd_log_access_permit_actions (empty)
              Enable  logging  of  the  named "permit" actions in
              SMTP server access  lists  (by  default,  the  SMTP
              server  logs  "reject"  actions  but  not  "permit"
              actions).

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  undeliverable  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,  local-
       host)
              The list of domains  that  are  delivered  via  the
              $local_transport mail delivery transport.

       inet_interfaces (all)
              The network interface addresses that this mail sys-
              tem receives mail on.

       proxy_interfaces (empty)
              The network interface addresses that this mail sys-
              tem  receives  mail on by way of a proxy or network
              address translation unit.

       inet_protocols (all)
              The Internet protocols Postfix will attempt to  use
              when making or accepting connections.

       local_recipient_maps             (proxy:unix:passwd.byname
       $alias_maps)
              Lookup  tables with all names or addresses of local
              recipients: a recipient address is local  when  its
              domain  matches $mydestination, $inet_interfaces or
              $proxy_interfaces.

       unknown_local_recipient_reject_code (550)
              The numerical Postfix  SMTP  server  response  code
              when    a   recipient   address   is   local,   and
              $local_recipient_maps specifies a  list  of  lookup
              tables that does not match the recipient.

       Parameters  concerning  known/unknown  recipients of relay
       destinations:

       relay_domains ($mydestination)
              What destination domains (and  subdomains  thereof)
              this system will relay mail to.

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

       unknown_relay_recipient_reject_code (550)
              The numerical Postfix SMTP server reply code when a
              recipient   address   matches  $relay_domains,  and
              relay_recipient_maps 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 Postfix SMTP server reply code when a recipient
              address matches $virtual_alias_domains,  and  $vir-
              tual_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   $vir-
              tual_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 Postfix SMTP server reply code when a recipient
              address matches $virtual_mailbox_domains, and $vir-
              tual_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 lim-
       its are implemented in co-operation with the anvil(8) ser-
       vice,  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 ses-
              sions that a remote SMTP client is allowed to nego-
              tiate with this service per time unit.

       Available in Postfix version 2.9 and later:

       smtpd_per_record_deadline (normal: no, overload: yes)
              Change  the  behavior  of  the  smtpd_timeout  time
              limit,  from  a time limit per read or write system
              call, to a time limit to send or receive a complete
              record  (an  SMTP command line, SMTP response line,
              SMTP message content line,  or  TLS  protocol  mes-
              sage).

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 con-
       trolled 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 delivering 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 control features.

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

       parent_domain_matches_subdomains (see 'postconf  -d'  out-
       put)
              What   Postfix   features   match   subdomains   of
              "domain.tld" automatically, instead of requiring an
              explicit ".domain.tld" pattern.

       smtpd_client_restrictions (empty)
              Optional restrictions that the Postfix SMTP  server
              applies  in  the  context  of  a  client 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 a client HELO command.

       smtpd_sender_restrictions (empty)
              Optional restrictions that the Postfix SMTP  server
              applies  in  the context of a client MAIL FROM com-
              mand.

       smtpd_recipient_restrictions (see 'postconf -d' output)
              Optional restrictions that the Postfix SMTP  server
              applies in the context of a client RCPT TO command,
              after smtpd_relay_restrictions.

       smtpd_etrn_restrictions (empty)
              Optional restrictions that the Postfix SMTP  server
              applies in the context of a client ETRN command.

       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 restric-
              tions.

       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 com-
              mand.

       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 restric-
              tion 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.

       Available in Postfix version 2.10 and later:

       smtpd_relay_restrictions               (permit_mynetworks,
       reject_unauth_destination)
              Access restrictions for mail relay control that the
              Postfix  SMTP  server applies in the context of the
              RCPT TO  command,  before  smtpd_recipient_restric-
              tions.

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 deliv-
       ered.  This feature is requested  via  the  reject_unveri-
       fied_sender    and    reject_unverified_recipient   access
       restrictions.  The status of verification probes is  main-
       tained by the verify(8) server.  See the file ADDRESS_VER-
       IFICATION_README for information about  how  to  configure
       and operate the Postfix sender/recipient address verifica-
       tion service.

       address_verify_poll_count (normal: 3, overload: 1)
              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 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 "post-
              master".

       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_unveri-
              fied_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  tempo-
              rary 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_temp-
       fail_action)
              The Postfix SMTP server's action when reject_unver-
              ified_sender fails due to a temporary error  condi-
              tion.

       unverified_recipient_tempfail_action        ($reject_temp-
       fail_action)
              The Postfix SMTP server's action when reject_unver-
              ified_recipient fails due to a temporary error con-
              dition.

       Available with Postfix 2.9 and later:

       address_verify_sender_ttl (0s)
              The time between changes in the time-dependent por-
              tion   of   address   verification   probe   sender
              addresses.

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_reverse_client, reject_rhsbl_sender or
              reject_rhsbl_recipient 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_plain-
              text_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  map-
              ping is rejected by the reject_unknown_client_host-
              name 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 restriction.

       Available in Postfix version 2.0 and later:

       default_rbl_reply (see 'postconf -d' output)
              The  default  Postfix 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 temporary error condi-
              tion.

       unknown_helo_hostname_tempfail_action       ($reject_temp-
       fail_action)
              The   Postfix    SMTP    server's    action    when
              reject_unknown_helo_hostname fails due to an tempo-
              rary 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  tem-
              porary 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  com-
              mands.

       double_bounce_sender (double-bounce)
              The sender address of postmaster notifications that
              are generated 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 termi-
              nating voluntarily.

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

       mynetworks (see 'postconf -d' output)
              The list of "trusted" remote 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  deliv-
              ered 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 direc-
              tory.

       recipient_delimiter (empty)
              The separator between user names and address exten-
              sions (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
       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)