When most people install a free software mail transport agent (MTA) they plumb for Postfix, Exim, qmail or Sendmail. Whilst these are all fine, they can be a little over the top for some smaller systems or systems where all you need is some kind of local MTA functionality. In these cases many people will install their favourite MTA anyway -- but there are more lightweight alternatives. Here I look at one of them: Smail.
Sendmail has a terrible reputation for security. While the latest releases are very good, past releases have been less than secure and that is where the reputation has come from.
Alternatives, like Postfix and qmail are proving to be much more popular, and have better history on security. All of this has led to Sendmail being removed from NetBSD (that's a digg link, used because some of the comments are worth reading).
Dspam filters spam with the best. In my installation, it stops over 98% of all spam: I’ve only had one false positive in the last year, and that was a message to the Dspam list that contained a real spam!
Administering Dspam is a breeze. No rules to configure, new users can automatically benefit from a global dictionary and quarantine management is simple. But getting a Dspam quarantine set up the first time, without losing any email, can challenge the most seasoned mail administrators.
If you are responsible for maintaining an internet-connected mail-server, then you have, no doubt, come to hate spam and the waste of resources which comes with it. When I first decided to lock down my own mail-server, I found many resources that helped in dealing with these unwanted messages. Each of them contained a trick or two, however very few of them were presented in the context of running a real server, and none of them demonstrated an entire filtering framework.