mailwrapper(8)
NAME
- mailwrapper - invoke appropriate MTA software based on con
- figuration 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 replacement programs that plug replace send
- mail(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 im - plicit 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 re
- placing
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.
DIAGNOSTICS
- The mailwrapper utility 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
- mail(1), mailq(1), newaliases(1), mailer.conf(5), period
- ic.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 "be - have differently if invoked with a different name" behavior of things
- like mailq(1)
should go away. - BSD December 16, 1998