Exim is a message transfer agent (MTA) developed at the University of Cambridge for use on Unix systems connected to the Internet. It is freely available under the terms of the GNU General Public Licence. In style it is similar to Smail 3, but its facilities are more general. There is a great deal of flexibility in the way mail can be routed, and there are extensive facilities for checking incoming mail. Exim can be installed in place of sendmail, although the configuration of exim is quite different to that of sendmail.
The current version of Exim is 4.20. See the Download page to get a copy.
Exim 3 and previous versions are now considered obsolete. Exim 3 is not being developed any further, nor is it being actively maintained, though if a really serious bug were found, it would be looked at.
The University of Cambridge Computing Service is hosting a fifth course on the Exim mail transfer agent on Monday 30 June to Wednesday 2 July 2003 in Robinson College, Cambridge. The course is suitable for those new to Exim as well as more experienced users. In addition to Dr Philip Hazel, there will be two external speakers. Further information and registration details can be found on http://www-tus.csx.cam.ac.uk/courses/exim/.
The new Exim 4 book is expected to be available in early May 2003. See the book website for further information.
The O'Reilly Exim 3 book is still available.