One of the reasons that most people don't use public key encryption to protect their e-mails is that the process is simply too arduous for everyday communications.
Open source projects like GNU Privacy Guard and GPGTools have made it easier for individuals to use PGP encryption, but managing the keys used in OpenPGP and other public-key encryption formats still requires effort. ... Pkware's just-announced Smartcrypt covers everything from mainframes to mobile devices. Smartcrypt lets organizations decide what kind of encryption and authentication they want to use, and it integrates into many common applications.
Read more at Ars Technica