Hushmail.com
I will never understand why you people use a free mail service with little to no e-mail security.
Hushmail uses 128bit SSL encryption to their servers, and OpenPGP for mail between Hushmail users, and if to users outside of the network if their PGP key has been uploaded to their servers.
You can also use their service with your domain, they calls it their Private Label service for $3.99 a month and worth every penny.