Old fashioned mail: Cone
I had one too many problems with kmail from KDE4 in my eee with Kubuntu, and sylpheed-claws is just unusable in a small screen (the huge widgets! the non-hidable things all over the interface!) I decided to get old fashioned and try a console mail reader.
I was a pine user for many years, and a mutt user for a while, and I was deeply disappointed that the last three years have been bad for these programs.
Just because you run in a terminal, there's no reason to be hard to configure! After spending 20 minutes trying to get a decent IMAP account setup (just two IMAP accounts) in alpine and another 10 wondering if mutt really had no place in the UI for account configuration (and whether the Debian/KUbuntu default "commented" config file is the product of hard drugs), I tried Cone.
It was bliss. It was all I remembered from pine years ago (on local accounts) only over IMAP.
Easy to configure, easy to use, quick, capable. I was in love all over again.
While I will keep using KMail on my main notebook under Arch Linux where I had no reliability problems whatsoever, I have Cone configured in my server's shell account and in the eee.