Good email client.

My new favorite email client is Thunderbird from Mozilla.

Sure works well and has TONS of options and supported platforms (client and server side).

http://www.mozilla.com/en-US/thunderbird/

I must say I'm not (yet) a Firefox bigot, but their email client is awesome and FREE.

Firefox works fine as long as you don't work against certain specialiazed Microsoft server applications on the other side...like OWA for example

I'm also not used to the keyboard shortcuts in Firefox or the way "tabs" are handled. Maybe registry hacks would help some of that. But I notice that Firefox is more compatible with HTTP servers every day it seems!