I've run the bases with Linux email clients. From Pine to Balsa to Arrow to Evolution to Kmail to Thunderbird the list leads like a science text book. But I'll give you one guess as to which client I always seem to return to. Did you guess Pine? You guessed correctly.
Email is one of those Microsoftian double-edged swords that can totally make or break your day. Any given email can bring down your email client due to scripting, corrupted attachments, memory leaks, yadda yadda yadda. And every one of them caused me headache after headache - except for Pine. Pine is the little email client that could. Sure Pine is a text-based only client. Sure Pine can't view images or html email. Pine can't show little smilies and allow you to click on a link to view a url. Pine won't hit a game winning home run. But Pine can serve as that trusty outfielder always waiting in the green for that long ball to sail into its glove.
What I like about Pine is its simplicity. It's text-only so its footprint is tiny. It's text-only so it's reliable. It's text-only so it can be used via a secure shell or (heaven forbid) telnet session. Pine is simply flexible.
Sure I know most emailers are hooked on bells and whistles that the Microsofts of the world have pimped. But this old-schooler knows that, when push comes to shove, the one networking application that I can always count on is Pine.
It may not be for everyone, but Pine hits a home run for me every time.
Pine. Its what's for dinner.