MH-MTS(8)                                               MH-MTS(8)

       mh-mts - the nmh interface to the message transport system



     MMDF (any release)



       nmh can use a wide range of message transport  systems  to
       deliver  mail.   Although  the  nmh  administrator usually
       doesn't get to choose which MTS to use (since it's already
       in place), this document briefly describes the interfaces.

       When communicating with SendMail, nmh always uses the SMTP
       to  post  mail.  Depending on the nmh configuration, Send-
       Mail may be invoked directly (via a fork and an exec),  or
       nmh may open a TCP/IP connection to the SMTP server on the

       When communicating with zmailer, the SendMail  compatibil-
       ity  program is required to be installed in /usr/lib.  nmh
       communicates with zmailer by using the SMTP.  It does this
       by  invoking  the  /usr/lib/sendmail compatibility program
       directly, with the `-bs' option.

       When communicating with MMDF, normally nmh uses the  "mm_"
       routines to post mail.  However, depending on the nmh con-
       figuration, nmh instead may open a  TCP/IP  connection  to
       the SMTP server on the localhost.

       If  you  are running a UNIX system with TCP/IP networking,
       then it is felt that the best  interface  is  achieved  by
       using  either SendMail or MMDF with the SMTP option.  This
       gives greater flexibility.   To  enable  this  option  you
       append  the /smtp suffix to the mts option in the nmh con-
       figuration.  This yields two  primary  advantages:  First,
       you  don't  have  to  know  where submit or SendMail live.
       This means that nmh binaries (e.g., post ) don't  have  to
       have  this  information  hard-coded,  or can run different
       programs altogether; and, second, you can post  mail  with
       the  server on different systems, so you don't need either
       MMDF or SendMail on your local host.  Big win in  conserv-
       ing  cycles and disk space.  Since nmh supports the notion
       of a server search-list in this respect, this approach can
       be  tolerant  of  faults.   Be  sure  to set "servers:" as
       described in mh-tailor(8) if you use this option.

       There are four disadvantages to  using  the  SMTP  option:
       First,  only UNIX systems with TCP/IP are supported.  Sec-
       ond, you need to have an SMTP server running somewhere  on
       any  network  your  local  host  can  reach.   Third, this
       bypasses any authentication mechanisms in  MMDF  or  Send-
       Mail.   Fourth,  the  file /etc/hosts is used for hostname
       lookups  (although  there  is  an  exception  file).    In
       response to these disadvantages though: First, there's got
       to be an SMTP server somewhere around  if  you're  in  the
       Internet  or  have  a  local  network.   Since  the server
       search-list is very general, a wide-range of  options  are
       possible.   Second, SMTP should be fixed to have authenti-
       cation mechanisms in it, like POP.  Third, nmh won't choke
       on  mail  to  hosts  whose official names it can't verify,
       it'll just plug along (and besides if you enable the  DUMB
       configuration  options,  nmh  ignores the hosts file alto-
       gether).  ^/etc/nmh/mts.conf~^nmh mts  configuration  file
       None MMDF-II: A Technical Review, Proceedings, Usenix Sum-
       mer '84 Conference
       SENDMAIL -- An Internetwork Mail Router
       mh-tailor(8), post(8) None None The /etc/nmh/mts.conf file
       ignores the information in the MMDF-II tailoring file.

[nmh-0.27]                    MH.6.8                            1