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MAILWRAPPER(8)          FreeBSD System Manager's Manual         MAILWRAPPER(8)

NAME
     mailwrapper - invoke appropriate MTA software based on configuration file

SYNOPSIS
     Special.  See below.

DESCRIPTION
     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 UNIX 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(1) and newaliases(1)
     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 hand 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 utility is designed to replace /usr/sbin/sendmail and to
     invoke an appropriate MTA instead of sendmail(8) based on configuration
     information placed in /etc/mail/mailer.conf.  This permits the
     administrator to configure which MTA is to be invoked on the system at
     run time.

     Other configuration files may need to be altered when replacing
     sendmail(8).  For example, if the replacement MTA does not support the -A
     option with mailq(1), daily_status_include_submit_mailq should be turned
     off in /etc/periodic.conf.

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

EXIT STATUS
     The mailwrapper utility exits 0 on success, and >0 if an error occurs.

DIAGNOSTICS
     The mailwrapper will print a diagnostic if its configuration file is
     missing or malformed, or does not contain a mapping for the name under
     which it was invoked.

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

HISTORY
     The mailwrapper utility first appeared in NetBSD 1.4 and then
     FreeBSD 4.0.

AUTHORS
     Perry E. Metzger <perry@piermont.com>

BUGS
     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(1) should go away.

FreeBSD 11.0-PRERELEASE         August 7, 2006         FreeBSD 11.0-PRERELEASE

NAME | SYNOPSIS | DESCRIPTION | FILES | EXIT STATUS | DIAGNOSTICS | SEE ALSO | HISTORY | AUTHORS | BUGS

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