Philip Hazel - University of Cambridge Computing Service

Exim 4

Exim is an MTA (that is, a replacement for sendmail) which runs on most flavours of Unix.

Probably its most distinguishing characteristic is the wide variety of ways in which it can be configured. This has made it attractive in a number of very different environments, from very large ISP servers to personal Linux boxes. Exim is GPL software, and there is now an O'Reilly book about it.

Over the last year I have been developing a major new release of Exim which is called Exim 4. There are major changes in the way Exim 4 implements policies for controlling incoming mail, and in the overall way in which it decides where to send messages. These changes mean that Exim 4 configurations are not backwards compatible with Exim 3, and upgrading is a non-trivial exercise. I have taken the opportunity of an incompatible upgrade to remove some obsolete features and reformulate others.

In my talk I will explain the reasons behind the decision to have such a large upheaval, and I will go into some detail about the way the new policy and delivery features work. However, I hope that the content of my talk, though technical, will be understandable by people who do not have a detailed knowledge of Exim.