Need to get a mail server up and running quickly? Linux.Ars has the goods on how to install and configure Postfix.
Years removed from the original release of Postfix, the Unix-based mail server is still serving oodles of people every day. Sendmail may have the largest market share in the Linux community, but Postfix is a much simpler setup, and is good for users who do not want to spend a lot of time configuring a mail server.
There's also a tutorial on using GPG from the command line to encrypt your valuable stuff, and much more.
http://feeds.feedburner.com/arstechnica/BAaf?m=1182