You could try claws mail. However it doesn't work very well for me - crashes more often than Windows. I didn't even manage to get it to send out a test mail before it crashes and exits (and yes I tried 5-6 times). In the end I installed Easy Debian + Thunderbird and copied my settings folder from my desktop and hey presto all my mail in my pocket.

Tip: Thunderbird (aka icedove in Debian) stores its stuff in /home/user/.icedove, if you have loads of mail you may run out of space because that partition is only 2GB and your optified apps live in there too. To get around this you can have the .icedove folder in /home/user/MyDocs then create a symlink to it in /home/user.