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SMTPD(8)                                                              SMTPD(8)

NAME
       smtpd - Postfix SMTP server

SYNOPSIS
       smtpd [generic Postfix daemon options]

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 Error Codes)
       RFC 2554 (AUTH command)
       RFC 2821 (SMTP protocol)
       RFC 2920 (SMTP Pipelining)
       RFC 3207 (STARTTLS command)
       RFC 3461 (SMTP DSN Extension)
       RFC 3463 (Enhanced Status Codes)

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  SMTP  clients  that
              implement  an  obsolete version of the AUTH command
              (RFC 2554).

       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 SMTP clients Postfix will not offer AUTH  sup-
              port 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
              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  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).

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.

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)
              The  name of a mail delivery transport that filters
              mail after it is queued.

BEFORE QUEUE EXTERNAL CONTENT INSPECTION CONTROLS
       As of version 2.1, the Postfix SMTP server can be  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_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 (2)
              The  mail filter protocol version and optional pro-
              tocol extensions for communication  with  a  Milter
              (mail filter) application.

       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 -n output)
              The macros that are sent to  Milter  (mail  filter)
              applications  after  completion  of an SMTP connec-
              tion.

       milter_helo_macros (see postconf -n output)
              The macros that are sent to  Milter  (mail  filter)
              applications after the SMTP HELO or EHLO command.

       milter_mail_macros (see postconf -n output)
              The  macros  that  are sent to Milter (mail filter)
              applications after the SMTP MAIL FROM command.

       milter_rcpt_macros (see postconf -n output)
              The macros that are sent to  Milter  (mail  filter)
              applications after the SMTP RCPT TO command.

       milter_data_macros (see postconf -n 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 -n output)
              The  macros  that  are  sent to version 3 or higher
              Milter (mail filter) applications after an  unknown
              SMTP command.

       milter_end_of_data_macros (see postconf -n 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  SMTP  clients are allowed to use the XFORWARD
              feature.

SASL AUTHENTICATION CONTROLS
       Postfix SASL support (RFC 2554) 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  SMTP  clients that
              implement an obsolete version of the  AUTH  command
              (RFC 2554).

       smtpd_sasl_auth_enable (no)
              Enable  SASL  authentication  in  the  Postfix SMTP
              server.

       smtpd_sasl_local_domain (empty)
              The name of the local SASL authentication realm.

       smtpd_sasl_security_options (noanonymous)
              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 SMTP clients Postfix will not offer AUTH  sup-
              port to.

       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 is  passed
              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.

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 (300s)
              The  time  limit  for Postfix SMTP server write and
              read operations during  TLS  startup  and  shutdown
              handshake procedures.

       smtpd_tls_CAfile (empty)
              The  file with the certificate of the certification
              authority (CA) that issued the Postfix SMTP  server
              certificate.

       smtpd_tls_CAfile (empty)
              The  file with the certificate of the certification
              authority (CA) that issued the Postfix SMTP  server
              certificate.

       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 (5)
              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 SMTP server cipher list at  manda-
              tory TLS security levels.

       smtpd_tls_mandatory_protocols (SSLv3, TLSv1)
              The  TLS  protocols  accepted  by  the Postfix SMTP
              server with mandatory TLS encryption.

       smtpd_tls_received_header (no)
              Request  that  the  Postfix  SMTP  server  produces
              Received:  message headers that include information
              about the protocol and cipher used, as well as  the
              client  CommonName  and  client  certificate issuer
              CommonName.

       smtpd_tls_req_ccert (no)
              With mandatory TLS  encryption,  require  a  remote
              SMTP  client certificate in order to allow TLS con-
              nections 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 (!aNULL:eNULL+kRSA)
              The OpenSSL cipherlist  for  "NULL"  grade  ciphers
              that provide authentication without encryption.

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
              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  encryp-
              tion.

       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 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  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.

       soft_bounce (no)
              Safety net to keep mail queued that would otherwise
              be returned to the sender.

       Available in Postfix version 2.1 and later:

       smtpd_authorized_xclient_hosts (empty)
              What SMTP clients are allowed to  use  the  XCLIENT
              feature.

KNOWN VERSUS UNKNOWN RECIPIENT CONTROLS
       As  of  Postfix  version 2.0, the SMTP server rejects mail
       for unknown recipients. This prevents the mail queue  from
       clogging  up  with  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 (ipv4)
              The  Internet protocols Postfix will attempt to use
              when making or accepting connections.

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

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

       Parameters concerning known/unknown  recipients  of  relay
       destinations:

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

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

       unknown_relay_recipient_reject_code (550)
              The numerical Postfix SMTP server reply code when a
              recipient  address  matches   $relay_domains,   and
              relay_recipient_maps  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    $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 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 (300s)
              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  connection  count,
              connection rate, or SMTP request rate restrictions.

       Available in Postfix version 2.3 and later:

       smtpd_client_new_tls_session_rate_limit (0)
              The maximal number of new (i.e., uncached) TLS ses-
              sions that a remote SMTP client is allowed to nego-
              tiate 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  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 (20)
              The  maximal  number of errors a remote SMTP client
              is allowed to make without delivering mail.

       smtpd_junk_command_limit (100)
              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  SMTP  server  access  restrictions in the
              context of a client SMTP connection request.

       smtpd_helo_required (no)
              Require that a remote SMTP client introduces itself
              at  the  beginning of an SMTP session with the HELO
              or EHLO command.

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

       smtpd_sender_restrictions (empty)
              Optional  restrictions that the Postfix SMTP server
              applies in the context of the MAIL FROM command.

       smtpd_recipient_restrictions           (permit_mynetworks,
       reject_unauth_destination)
              The  access  restrictions  that  the  Postfix  SMTP
              server  applies  in the context of the RCPT TO com-
              mand.

       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 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.

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 (3)
              How  many  times to query the verify(8) service for
              the completion of an address  verification  request
              in progress.

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

       address_verify_sender (postmaster)
              The sender address to use in  address  verification
              probes.

       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.

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
              when  a  client  is  rejected  by  an access(5) map
              restriction.

       defer_code (450)
              The numerical Postfix  SMTP  server  response  code
              when  a  remote  SMTP client request is rejected by
              the "defer" restriction.

       invalid_hostname_reject_code (501)
              The numerical Postfix  SMTP  server  response  code
              when  the  client HELO or EHLO command parameter is
              rejected   by   the    reject_invalid_helo_hostname
              restriction.

       maps_rbl_reject_code (554)
              The  numerical  Postfix  SMTP  server response code
              when a remote SMTP client request is blocked by the
              reject_rbl_client,             reject_rhsbl_client,
              reject_rhsbl_sender    or    reject_rhsbl_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 SMTP server  response  template  for  a
              request  that  is rejected by an RBL-based restric-
              tion.

       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.

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 the next service request
              before exiting.

       max_use (100)
              The maximal number of connection requests before  a
              Postfix daemon process terminates.

       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 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 (postfix)
              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  causes  the  Postfix SMTP
              server to immediately terminate the session with  a
              221 code.

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

                                                                      SMTPD(8)