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<html> <head> </head> <body> <pre>



SMTPD(8)                                                 SMTPD(8)


<b>NAME</b>
       smtpd - Postfix SMTP server

<b>SYNOPSIS</b>
       <b>smtpd</b> [generic Postfix daemon options]

<b>DESCRIPTION</b>
       The  SMTP  server  accepts network connection requests and
       performs zero or more SMTP  transactions  per  connection.
       Each received message is piped through the <a href="cleanup.8.html"><b>cleanup</b>(8)</a> dae-
       mon, and is placed into the <b>incoming</b> queue as  one  single
       queue  file.   For  this  mode  of  operation, the program
       expects to be run from the <a href="master.8.html"><b>master</b>(8)</a> process manager.

       Alternatively, the SMTP server takes an  established  con-
       nection  on  standard input and deposits messages directly
       into the <b>maildrop</b> queue.  In  this  so-called  stand-alone
       mode,  the SMTP server can accept mail even while the mail
       system is not running.

       The SMTP server implements a variety of policies for  con-
       nection  requests,  and for parameters given to <b>HELO,</b> <b>MAIL</b>
       <b>FROM,</b> <b>VRFY</b> and <b>RCPT</b> <b>TO</b> commands. They are  detailed  below
       and in the <b>main.cf</b> configuration file.

<b>SECURITY</b>
       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.

<b>STANDARDS</b>
       <a href="http://www.faqs.org/rfcs/rfc821.html">RFC 821</a> (SMTP protocol)
       <a href="http://www.faqs.org/rfcs/rfc1123.html">RFC 1123</a> (Host requirements)
       <a href="http://www.faqs.org/rfcs/rfc1651.html">RFC 1651</a> (SMTP service extensions)
       <a href="http://www.faqs.org/rfcs/rfc1652.html">RFC 1652</a> (8bit-MIME transport)
       <a href="http://www.faqs.org/rfcs/rfc1854.html">RFC 1854</a> (SMTP Pipelining)
       <a href="http://www.faqs.org/rfcs/rfc1870.html">RFC 1870</a> (Message Size Declaration)
       <a href="http://www.faqs.org/rfcs/rfc1985.html">RFC 1985</a> (ETRN command) (partial)

<b>DIAGNOSTICS</b>
       Problems and transactions are logged to <b>syslogd</b>(8).

       Depending  on the setting of the <b>notify</b><i>_</i><b>classes</b> parameter,
       the postmaster is notified of bounces, protocol  problems,
       policy violations, and of other trouble.

<b>BUGS</b>
       <a href="http://www.faqs.org/rfcs/rfc1985.html">RFC  1985</a>  is  implemented  by  forcing  delivery  of  all
       deferred mail.

<b>CONFIGURATION</b> <b>PARAMETERS</b>
       The following <b>main.cf</b> parameters are  especially  relevant
       to  this  program. See the Postfix <b>main.cf</b> file for syntax
       details and for default values.  Use  the  <b>postfix</b>  <b>reload</b>



                                                                1





SMTPD(8)                                                 SMTPD(8)


       command after a configuration change.

<b>Compatibility</b> <b>controls</b>
       <b>strict</b><i>_</i><b>rfc821</b><i>_</i><b>envelopes</b>
              Disallow  non-<a href="http://www.faqs.org/rfcs/rfc821.html">RFC 821</a> style addresses in envelopes.
              For example, allow <a href="http://www.faqs.org/rfcs/rfc822.html">RFC822</a>-style address forms  with
              comments, like Sendmail does.

<b>Miscellaneous</b>
       <b>always</b><i>_</i><b>bcc</b>
              Address  to send a copy of each message that enters
              the system.

       <b>command</b><i>_</i><b>directory</b>
              Location  of  Postfix  support  commands  (default:
              <b>$program</b><i>_</i><b>directory</b>).

       <b>debug</b><i>_</i><b>peer</b><i>_</i><b>level</b>
              Increment  in  verbose  logging level when a remote
              host  matches  a  pattern  in  the  <b>debug</b><i>_</i><b>peer</b><i>_</i><b>list</b>
              parameter.

       <b>debug</b><i>_</i><b>peer</b><i>_</i><b>list</b>
              List  of  domain or network patterns. When a remote
              host matches a pattern, increase the  verbose  log-
              ging   level   by   the  amount  specified  in  the
              <b>debug</b><i>_</i><b>peer</b><i>_</i><b>level</b> parameter.

       <b>error</b><i>_</i><b>notice</b><i>_</i><b>recipient</b>
              Recipient   of    protocol/policy/resource/software
              error notices.

       <b>hopcount</b><i>_</i><b>limit</b>
              Limit the number of <b>Received:</b> message headers.

       <b>notify</b><i>_</i><b>classes</b>
              List of error classes. Of special interest are:

       <b>local</b><i>_</i><b>recipient</b><i>_</i><b>maps</b>
              List  of  maps  with  user  names that are local to
              <b>$myorigin</b> or <b>$inet</b><i>_</i><b>interfaces</b>. If this parameter is
              defined,  then  the  SMTP  server  rejects mail for
              unknown local users.

              <b>policy</b> When a client violates any  policy,  mail  a
                     transcript of the entire SMTP session to the
                     postmaster.

              <b>protocol</b>
                     When a client violates the SMTP protocol  or
                     issues  an  unimplemented  command,  mail  a
                     transcript of the entire SMTP session to the
                     postmaster.




                                                                2





SMTPD(8)                                                 SMTPD(8)


       <b>smtpd</b><i>_</i><b>banner</b>
              Text  that  follows the <b>220</b> status code in the SMTP
              greeting banner.

       <b>smtpd</b><i>_</i><b>recipient</b><i>_</i><b>limit</b>
              Restrict the number of  recipients  that  the  SMTP
              server accepts per message delivery.

       <b>smtpd</b><i>_</i><b>timeout</b>
              Limit  the  time  to  send a server response and to
              receive a client request.

<b>Resource</b> <b>controls</b>
       <b>line</b><i>_</i><b>length</b><i>_</i><b>limit</b>
              Limit the amount of memory in bytes  used  for  the
              handling of partial input lines.

       <b>message</b><i>_</i><b>size</b><i>_</i><b>limit</b>
              Limit the total size in bytes of a message, includ-
              ing on-disk storage for envelope information.

       <b>queue</b><i>_</i><b>minfree</b>
              Minimal amount of free space in bytes in the  queue
              file  system for the SMTP server to accept any mail
              at all.

<b>Tarpitting</b>
       <b>smtpd</b><i>_</i><b>error</b><i>_</i><b>sleep</b><i>_</i><b>time</b>
              Time to wait in seconds before sending a 4xx or 5xx
              server error response.

       <b>smtpd</b><i>_</i><b>soft</b><i>_</i><b>error</b><i>_</i><b>limit</b>
              When an SMTP client has made this number of errors,
              wait <i>error_count</i> seconds before responding  to  any
              client request.

       <b>smtpd</b><i>_</i><b>hard</b><i>_</i><b>error</b><i>_</i><b>limit</b>
              Disconnect  after  a client has made this number of
              errors.

       <b>smtpd</b><i>_</i><b>junk</b><i>_</i><b>command</b><i>_</i><b>limit</b>
              Limit the number of times a client can issue a junk
              command  such  as  NOOP,  VRFY, ETRN or RSET in one
              SMTP session before it  is  penalized  with  tarpit
              delays.

<b>UCE</b> <b>control</b> <b>restrictions</b>
       <b>smtpd</b><i>_</i><b>client</b><i>_</i><b>restrictions</b>
              Restrict what clients may connect to this mail sys-
              tem.

       <b>smtpd</b><i>_</i><b>helo</b><i>_</i><b>required</b>
              Require that clients introduce  themselves  at  the
              beginning of an SMTP session.



                                                                3





SMTPD(8)                                                 SMTPD(8)


       <b>smtpd</b><i>_</i><b>helo</b><i>_</i><b>restrictions</b>
              Restrict  what client hostnames are allowed in <b>HELO</b>
              and <b>EHLO</b> commands.

       <b>smtpd</b><i>_</i><b>sender</b><i>_</i><b>restrictions</b>
              Restrict what sender addresses are allowed in  <b>MAIL</b>
              <b>FROM</b> commands.

       <b>smtpd</b><i>_</i><b>recipient</b><i>_</i><b>restrictions</b>
              Restrict  what  recipient  addresses are allowed in
              <b>RCPT</b> <b>TO</b> commands.

       <b>smtpd</b><i>_</i><b>etrn</b><i>_</i><b>restrictions</b>
              Restrict what domain names can be used in <b>ETRN</b> com-
              mands, and what clients may issue <b>ETRN</b> commands.

       <b>allow</b><i>_</i><b>untrusted</b><i>_</i><b>routing</b>
              Allow  untrusted  clients to specify addresses with
              sender-specified routing.  Enabling this  opens  up
              nasty  relay  loopholes involving trusted backup MX
              hosts.

       <b>restriction</b><i>_</i><b>classes</b>
              Declares the name of zero or more  parameters  that
              contain  a  list  of UCE restrictions. The names of
              these parameters can then be used  instead  of  the
              restriction lists that they represent.

       <b>maps</b><i>_</i><b>rbl</b><i>_</i><b>domains</b>
              List  of  DNS domains that publish the addresses of
              blacklisted hosts.

       <b>relay</b><i>_</i><b>domains</b>
              Restrict what domains or networks this mail  system
              will relay mail from or to.

<b>UCE</b> <b>control</b> <b>responses</b>
       <b>access</b><i>_</i><b>map</b><i>_</i><b>reject</b><i>_</i><b>code</b>
              Server  response  when  a client violates an access
              database restriction.

       <b>invalid</b><i>_</i><b>hostname</b><i>_</i><b>reject</b><i>_</i><b>code</b>
              Server  response  when  a   client   violates   the
              <b>reject</b><i>_</i><b>invalid</b><i>_</i><b>hostname</b> restriction.

       <b>maps</b><i>_</i><b>rbl</b><i>_</i><b>reject</b><i>_</i><b>code</b>
              Server   response   when   a  client  violates  the
              <b>maps</b><i>_</i><b>rbl</b><i>_</i><b>domains</b> restriction.

       <b>reject</b><i>_</i><b>code</b>
              Response code when  the  client  matches  a  <b>reject</b>
              restriction.





                                                                4





SMTPD(8)                                                 SMTPD(8)


       <b>relay</b><i>_</i><b>domains</b><i>_</i><b>reject</b><i>_</i><b>code</b>
              Server  response  when a client attempts to violate
              the mail relay policy.

       <b>unknown</b><i>_</i><b>address</b><i>_</i><b>reject</b><i>_</i><b>code</b>
              Server  response  when  a   client   violates   the
              <b>reject</b><i>_</i><b>unknown</b><i>_</i><b>address</b> restriction.

       <b>unknown</b><i>_</i><b>client</b><i>_</i><b>reject</b><i>_</i><b>code</b>
              Server  response  when  a client without address to
              name mapping  violates  the  <b>reject</b><i>_</i><b>unknown</b><i>_</i><b>clients</b>
              restriction.

       <b>unknown</b><i>_</i><b>hostname</b><i>_</i><b>reject</b><i>_</i><b>code</b>
              Server   response   when   a  client  violates  the
              <b>reject</b><i>_</i><b>unknown</b><i>_</i><b>hostname</b> restriction.

<b>SEE</b> <b>ALSO</b>
       <a href="cleanup.8.html">cleanup(8)</a> message canonicalization
       <a href="master.8.html">master(8)</a> process manager
       syslogd(8) system logging

<b>LICENSE</b>
       The Secure Mailer license must be  distributed  with  this
       software.

<b>AUTHOR(S)</b>
       Wietse Venema
       IBM T.J. Watson Research
       P.O. Box 704
       Yorktown Heights, NY 10598, USA


























                                                                5


</pre> </body> </html>