From their site....
CryptoMail.org devotes its energy to promote the freedom of private communications. By developing and distributing an end-to-end secure Email system under the GNU General Public License, we hope to inspire the most talented programmers around the world to help create a secure environment for people to exchange information over the Internet.
The main objective of CryptoMail.org is to provide a community where programmers who share our vision, give the most accessible, reliable, and secure communications tools to people. We will focus on developing, distributing, maintaining and serving the most secure end-to-end Email system for the Internet community. We want everyone to access secure Email services, thus we develop an Email system that allows people to use or host the system on almost any computer and platform. We provide this secure Email system by ensuring two key security features:
Security at the Transport Level
All communications between the user and the server are done by a way of an encrypted session. This discourages eavesdroppers at the network layer.
End-to-End Message Security
Exchange of messages within our Email system employs a message layer encryption using a hybrid symmetric and public/private key scheme. This effectively prevents anyone from reading the contents of the message except the intended recipient.