Exim is a mail transfer agent (MTA) used on Unix-like operating systems. 
It is freely available under the GNU GPL and it aims to be a general 
and flexible mailer with extensive facilities for checking incoming e-mail.

Exim was orginally written by Philip Hazel for use in the University 
of Cambridge Computing Services e-mail systems. 

Before you can build Exim, you have to create an "exim" user and group:
      #	groupadd -g 222 exim
      #	useradd -d /var/spool/exim -g exim -s /bin/false -u 222 exim
The recommended uid/gid is 222, but others are fine if you prefer - 
see http://slackbuilds.org/uid_gid.txt for other recommendations.

There's no "configure" script; instead Exim is configured by editing a well
documented Makefile, which is then included during the build process.  The
provided "exim.Makefile" will build an all-purpose Exim daemon with almost
all of the features that will work on a standard Slackware system.

Exim can be integrated with other email tools such as Clamav, Spamassassin,
Bogofilter, and others available at Slackbuilds.org.  You might also be
interested in the "exim-html" package, an extensive documentation for Exim.

WARNING: this package is intended as a drop-in replacement for Sendmail.
As a result, there are some inevitable filename conflicts between Sendmail
and Exim.  REMOVE SENDMAIL BEFORE INSTALLING THIS PACKAGE!