There are a gazillion email applications for Unix, and its a good thing because there is a wide range of opinion about how email should work.
I have been running elm for years (ten years, I guess). It is a good solid program. However, if I am running a graphical workstation, it would seem like my email application would be the most important GUI program I have. There are other drawbacks: I must run elm where my mail spools, and there is little support for HTML and weird (Microsoft) character sets.
So, I set out to choose a GUI email program. I made a list of requirements (the most important being IMAP support), and I went through the FreeBSD ports collection to try things out. I was a little disgusted at some of the things I found. IMHO, unfinished programs don't belong in the ports collection. IMAP support was weak or non-existant in most of the programs I evaluated. Finally, I choose a Gnome application called Sylpheed.