Encrypt your email:

E-mail can be easily rerouted and read by unintended third parties; messages are often saved for indefinite periods of time. Presently, technologies exist that allow you to encrypt your messages in order to protect their privacy. Some e-mail programs (i.e., Internet Explorer, Outlook, and Netscape Messenger) have encryption. Pretty Good Privacy (PGP), a popular encryption software, is free for non-commercial use.

Read more on PGP and download the encryption software at http://web.mit.edu/network/pgp.html.