NAME    [Toc]    [Back]

     mailwrapper - invoke appropriate MTA software based on  configuration file

SYNOPSIS    [Toc]    [Back]

     Special.  See below.

DESCRIPTION    [Toc]    [Back]

     At  one  time,  the  only Mail Transfer Agent (MTA) software
easily available
     was sendmail(8).  As a result of this, most Mail User Agents
(MUAs) such
     as  mail(1) had the path and calling conventions expected by
sendmail(8)
     compiled in.

     Times have changed, however.  On a modern system, the administrator may
     wish to use one of several available MTAs.

     It  would  be difficult to modify all MUA software typically
available on a
     system, so most of the  authors  of  alternative  MTAs  have
written their
     front  end  message submission programs so that they use the
same calling
     conventions as sendmail(8) and may be put into place instead
of
     sendmail(8) in /usr/sbin/sendmail.

     sendmail(8)  also  typically  has aliases named mailq(8) and
newaliases(8)
     linked to it.  The program knows to behave differently  when
its argv[0]
     is  ``mailq''  or  ``newaliases'' and behaves appropriately.
Typically, replacement
 MTAs provide similar functionality, either through
a program
     that  also  switches  behavior  based  on  calling  name, or
through a set of
     programs that provide similar functionality.

     Although having drop-in replacements for  sendmail(8)  helps
in installing
     alternative  MTAs, it essentially makes the configuration of
the system
     depend on hard installing new programs in /usr.  This  leads
to configuration
  problems  for many administrators, since they may wish
to install a
     new MTA without altering the system  provided  /usr.   (This
may be, for example,
  to  avoid having upgrade problems when a new version
of the system
     is installed over the old.)  They may  also  have  a  shared
/usr among several
  machines,  and may wish to avoid placing implicit configuration information
 in a read-only /usr.

     The   mailwrapper   program   is   designed    to    replace
/usr/sbin/sendmail and to
     invoke  an  appropriate  MTA instead of sendmail(8) based on
configuration
     information placed in /etc/mailer.conf.   This  permits  the
administrator
     to configure which MTA is to be invoked on the system at run
time.

FILES    [Toc]    [Back]

     Configuration for mailwrapper is kept in /etc/mailer.conf.
     /usr/sbin/sendmail is typically  set  up  as  a  symlink  to
mailwrapper which
     is not usually invoked on its own.

DIAGNOSTICS    [Toc]    [Back]

     mailwrapper  will return an error value and print a diagnostic if its configuration
 file is missing or malformed, or does not contain
a mapping
     for the name under which mailwrapper was invoked.

SEE ALSO    [Toc]    [Back]

     mail(1),   mailer.conf(5),  mailq(8),  newaliases(8),  sendmail(8)

AUTHORS    [Toc]    [Back]

     Perry E. Metzger <[email protected]>

BUGS    [Toc]    [Back]

     The entire reason this program exists is a crock.   Instead,
a command for
     how  to submit mail should be standardized, and all the "behave differently
 if invoked with a different name" behavior of things like
mailq(8)
     should go away.

OpenBSD      3.6                        December     16,     1998