[maqr]

SSL is for end-point to end-point security. SSL does not attempt to solve the problem of either end being compromised. This means that SSL won't help you if your computer is infected with rogue software or if the server you're talking to is compromised.

SSL does, however, help to prevent eavesdropping between point A and point B.

[jamespo]

Worthwhile if you use wireless networks, particularly unencrypted ones to access your email.

And with the cost of a godaddy or similar certificate so low, well worth implementing on your own box.