Evolution

I've also used Evolution for years, but it definitely has _not_ worked great. Crashes weren't too common, but anything more often than "never" is too often for me. Usually Evolution would have more subtle -- but equally data-destroying -- bugs, such as lock ups in the editor, drag-n-drop of messages causing a lockup (which in turn made the whole damn X session unusable, since the X grab was still in effect), and so on.

Switching to Thunderbird has made my life so much nicer.