SMTP(8) SMTP(8)

NAME
       smtp - Postfix remote delivery via SMTP

SYNOPSIS
       ssmmttpp [generic Postfix daemon options]

DESCRIPTION
       The SMTP client processes message delivery requests from the queue man-
       ager. Each request specifies a queue file, a sender address,  a  domain
       or host to deliver to, and recipient information.  This program expects
       to be run from the mmaasstteerr(8) process manager.

       The SMTP client updates the queue file and  marks  recipients  as  fin-
       ished,  or  it  informs the queue manager that delivery should be tried
       again at a  later  time.  Delivery  status  reports  are  sent  to  the
       bboouunnccee(8), ddeeffeerr(8) or ttrraaccee(8) daemon as appropriate.

       The  SMTP  client  looks  up a list of mail exchanger addresses for the
       destination host, sorts the list by preference, and  connects  to  each
       listed address until it finds a server that responds.

       When  a  server  is not reachable, or when mail delivery fails due to a
       recoverable error condition, the SMTP client will try  to  deliver  the
       mail to an alternate host.

SSEECCUURRIITTYY
       The  SMTP  client  is  moderately  security-sensitive. It talks to SMTP
       servers and to DNS servers on the network. The SMTP client can  be  run
       chrooted at fixed low privilege.

STANDARDS       RFC 821 (SMTP protocol)
       RFC 822 (ARPA Internet Text Messages)
       RFC 1651 (SMTP service extensions)
       RFC 1652 (8bit-MIME transport)
       RFC 1870 (Message Size Declaration)
       RFC 2045 (MIME: Format of Internet Message Bodies)
       RFC 2046 (MIME: Media Types)
       RFC 2554 (AUTH command)
       RFC 2821 (SMTP protocol)
       RFC 2920 (SMTP Pipelining)

DIAGNOSTICS       Problems  and transactions are logged to ssyyssllooggdd(8).  Corrupted message
       files are marked so that the queue manager can move them to the ccoorrrruupptt
       queue for further inspection.

       Depending  on the setting of the nnoottiiffyyccllaasssseess parameter, the postmas-
       ter is notified of bounces, protocol problems, and of other trouble.

CCOONNFFIIGGUURRAATTIIOONN PPAARRAAMMEETTEERRSS
       Changes to mmaaiinn..ccff are picked up automatically,  as  smtp(8)  processes
       run for only a limited amount of time. Use the command "ppoossttffiixx rreellooaadd"
       to speed up a change.

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

CCOOMMPPAATTIIBBIILLIITTYY CCOONNTTRROOLLSS
       iiggnnoorreemmxxllooookkuuppeerrrroorr ((nnoo))
              Ignore DNS MX lookups that produce no response.

       ssmmttppaallwwaayysssseennddeehhlloo ((yyeess))
              Always send EHLO at the start of an SMTP session.

       ssmmttppnneevveerrsseennddeehhlloo ((nnoo))
              Never send EHLO at the start of an SMTP session.

       ssmmttppddeeffeerriiffnnoommxxaaddddrreessssffoouunndd ((nnoo))
              Defer mail delivery when no MX record resolves to an IP address.

       ssmmttpplliinneelleennggtthhlliimmiitt ((999900))
              The maximal length of message header and body lines that Postfix
              will send via SMTP.

       ssmmttppppiixxwwoorrkkaarroouunnddddeellaayyttiimmee ((1100ss))
              How   long   the  Postfix  SMTP  client  pauses  before  sending
              "."  in  order  to  work   around   the   PIX   firewall
              "." bug.

       ssmmttppppiixxwwoorrkkaarroouunnddtthhrreesshhoollddttiimmee ((550000ss))
              How  long  a  message  must  be  queued  before the PIX firewall
              "." bug workaround is turned on.

       ssmmttppqquuootteerrffcc882211eennvveellooppee ((yyeess))
              Quote addresses in SMTP  MAIL  FROM  and  RCPT  TO  commands  as
              required by RFC 821.

       ssmmttppsskkiipp55xxxxggrreeeettiinngg ((yyeess))
              Skip SMTP servers that greet with a 5XX status code (go away, do
              not try again later).

       ssmmttppsskkiippqquuiittrreessppoonnssee ((yyeess))
              Do not wait for the response to the SMTP QUIT command.

       Available in Postfix version 2.0 and earlier:

       ssmmttppsskkiipp44xxxxggrreeeettiinngg ((yyeess))
              Skip SMTP servers that greet with a 4XX status  code  (go  away,
              try again later).

MMIIMMEE PPRROOCCEESSSSIINNGG CCOONNTTRROOLLSS
       Available in Postfix version 2.0 and later:

       ddiissaabblleemmiimmeeoouuttppuuttccoonnvveerrssiioonn ((nnoo))
              Disable the conversion of 8BITMIME format to 7BIT format.

       mmiimmeebboouunnddaarryylleennggtthhlliimmiitt ((22004488))
              The maximal length of MIME multipart boundary strings.

       mmiimmeenneessttiinngglliimmiitt ((110000))
              The  maximal  nesting level of multipart mail that the MIME pro-
              cessor will handle.

EEXXTTEERRNNAALL CCOONNTTEENNTT IINNSSPPEECCTTIIOONN CCOONNTTRROOLLSS
       Available in Postfix version 2.1 and later:

       ssmmttppsseennddxxffoorrwwaarrddccoommmmaanndd ((nnoo))
              Send the non-standard XFORWARD command  when  the  Postfix  SMTP
              server EHLO response announces XFORWARD support.

SSAASSLL AAUUTTHHEENNTTIICCAATTIIOONN CCOONNTTRROOLLSS
       ssmmttppssaassllaauutthheennaabbllee ((nnoo))
              Enable SASL authentication in the Postfix SMTP client.

       ssmmttppssaassllppaasssswwoorrddmmaappss ((eemmppttyy))
              Optional  SMTP  client  lookup tables with one username:password
              entry per remote hostname or domain.

       ssmmttppssaassllsseeccuurriittyyooppttiioonnss ((nnooppllaaiinntteexxtt,, nnooaannoonnyymmoouuss))
              What  authentication  mechanisms  the  Postfix  SMTP  client  is
              allowed to use.

RREESSOOUURRCCEE AANNDD RRAATTEE CCOONNTTRROOLLSS
       ssmmttppddeessttiinnaattiioonnccoonnccuurrrreennccyylliimmiitt        (($$ddeeffaauullttddeessttiinnaattiioonnccoonnccuurr-
       rreennccyylliimmiitt))
              The  maximal  number of parallel deliveries to the same destina-
              tion via the smtp message delivery transport.

       ssmmttppddeessttiinnaattiioonnrreecciippiieennttlliimmiitt (($$ddeeffaauullttddeessttiinnaattiioonnrreecciippiieennttlliimmiitt))
              The maximal number of recipients per delivery via the smtp  mes-
              sage delivery transport.

       ssmmttppccoonnnneeccttttiimmeeoouutt ((3300ss))
              The  SMTP  client time limit for completing a TCP connection, or
              zero (use the operating system built-in time limit).

       ssmmttpphheelloottiimmeeoouutt ((330000ss))
              The SMTP client time limit for sending the HELO or EHLO command,
              and for receiving the initial server response.

       ssmmttppxxffoorrwwaarrddttiimmeeoouutt ((330000ss))
              The SMTP client time limit for sending the XFORWARD command, and
              for receiving the server response.

       ssmmttppmmaaiillttiimmeeoouutt ((330000ss))
              The SMTP client time limit for sending the  MAIL  FROM  command,
              and for receiving the server response.

       ssmmttpprrccppttttiimmeeoouutt ((330000ss))
              The SMTP client time limit for sending the SMTP RCPT TO command,
              and for receiving the server response.

       ssmmttppddaattaaiinniittttiimmeeoouutt ((112200ss))
              The SMTP client time limit for sending the  SMTP  DATA  command,
              and for receiving the server response.

       ssmmttppddaattaaxxffeerrttiimmeeoouutt ((118800ss))
              The SMTP client time limit for sending the SMTP message content.

       ssmmttppddaattaaddoonneettiimmeeoouutt ((660000ss))
              The SMTP client time limit for sending the  SMTP  ".",  and  for
              receiving the server response.

       ssmmttppqquuiittttiimmeeoouutt ((330000ss))
              The SMTP client time limit for sending the QUIT command, and for
              receiving the server response.

       Available in Postfix version 2.1 and later:

       ssmmttppmmxxaaddddrreesssslliimmiitt ((00))
              The maximal number of MX (mail exchanger) IP addresses that  can
              result from mail exchanger lookups, or zero (no limit).

       ssmmttppmmxxsseessssiioonnlliimmiitt ((22))
              The  maximal number of SMTP sessions per delivery request before
              giving up or delivering to a fall-back relay host, or  zero  (no
              limit).

       ssmmttpprrsseettttiimmeeoouutt ((112200ss))
              The SMTP client time limit for sending the RSET command, and for
              receiving the server response.

TTRROOUUBBLLEE SSHHOOOOTTIINNGG CCOONNTTRROOLLSS
       ddeebbuuggppeeeerrlleevveell ((22))
              The increment in verbose logging level when a remote  client  or
              server matches a pattern in the debugpeerlist parameter.

       ddeebbuuggppeeeerrlliisstt ((eemmppttyy))
              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 $debugpeerlevel.

       eerrrroorrnnoottiicceerreecciippiieenntt ((ppoossttmmaasstteerr))
              The  recipient  of  postmaster notifications about mail delivery
              problems that are caused by policy, resource, software or proto-
              col errors.

       nnoottiiffyyccllaasssseess ((rreessoouurrccee,, ssooffttwwaarree))
              The list of error classes that are reported to the postmaster.

MMIISSCCEELLLLAANNEEOOUUSS CCOONNTTRROOLLSS
       bbeessttmmxxttrraannssppoorrtt ((eemmppttyy))
              Where  the  Postfix  SMTP  client  should  deliver  mail when it
              detects a "mail loops back to myself" error condition.

       ccoonnffiiggddiirreeccttoorryy ((sseeee ''ppoossttccoonnff -dd'' oouuttppuutt))
              The default location of the Postfix main.cf and  master.cf  con-
              figuration files.

       ddaaeemmoonnttiimmeeoouutt ((1188000000ss))
              How  much  time  a  Postfix  daemon process may take to handle a
              request before it is terminated by a built-in watchdog timer.

       ddiissaabblleeddnnssllooookkuuppss ((nnoo))
              Disable DNS lookups in the Postfix SMTP and LMTP clients.

       ffaallllbbaacckkrreellaayy ((eemmppttyy))
              Optional list of relay hosts for SMTP destinations that can't be
              found or that are unreachable.

       iinneettiinntteerrffaacceess ((aallll))
              The  network  interface addresses that this mail system receives
              mail on.

       iippccttiimmeeoouutt ((33660000ss))
              The time limit for sending  or  receiving  information  over  an
              internal communication channel.

       mmaaxxiiddllee ((110000ss))
              The  maximum  amount of time that an idle Postfix daemon process
              waits for the next service request before exiting.

       mmaaxxuussee ((110000))
              The maximal number of connection requests before a Postfix  dae-
              mon process terminates.

       pprroocceessssiidd ((rreeaadd-oonnllyy))
              The process ID of a Postfix command or daemon process.

       pprroocceessssnnaammee ((rreeaadd-oonnllyy))
              The process name of a Postfix command or daemon process.

       pprrooxxyyiinntteerrffaacceess ((eemmppttyy))
              The  network  interface addresses that this mail system receives
              mail on by way of a proxy or network address translation unit.

       ssmmttppbbiinnddaaddddrreessss ((eemmppttyy))
              An optional numerical  network  address  that  the  SMTP  client
              should bind to when making a connection.

       ssmmttpphheelloonnaammee (($$mmyyhhoossttnnaammee))
              The hostname to send in the SMTP EHLO or HELO command.

       ssmmttpphhoossttllooookkuupp ((ddnnss))
              What mechanisms when the SMTP client uses to look up a host's IP
              address.

       ssmmttpprraannddoommiizzeeaaddddrreesssseess ((yyeess))
              Randomize the order of equal-preference MX host addresses.

       ssyyssllooggffaacciilliittyy ((mmaaiill))
              The syslog facility of Postfix logging.

       ssyyssllooggnnaammee ((ppoossttffiixx))
              The mail system name that is prepended to the  process  name  in
              syslog  records,  so  that  "smtpd" becomes, for example, "post-
              fix/smtpd".

SEE ALSO
       qmgr(8), queue manager
       bounce(8), delivery status reports
       postconf(5), configuration parameters
       master(8), process manager
       syslogd(8), system logging

README FILES       Use "ppoossttccoonnff rreeaaddmmeeddiirreeccttoorryy" or "ppoossttccoonnff hhttmmllddiirreeccttoorryy" to  locate
       this information.
       SASLREADME, Postfix SASL howto

LLIICCEENNSSEE
       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



                                                                       SMTP(8)