Secure your email on Mac OS X
Good lord, this
is a good link. All of this information is available elsewhere, of course, but this is a great place to read up on the whys and hows of using SSH to retrieve your email a bit more securely.
A lot of the comments criticize not just saying "turn on SSL for IMAP or POP", but there are a LOT of major ISPs who don't offer that functionality (*cough*Earthlink*cough*).
Read it even if you don't have a Mac.