MailCloak is Global Web Security Systems breakthrough encryption program. MailCloak for Mail Clients was designed from the ground up to be the first encryption program for all mail clients, while making GnuPG public-key encryption so simple anyone can use it. MailCloak works with Outlook, Outlook Express, Thunderbird, Eudora and more. MailCloak uses the Gnu Privacy Guard so it's compatible with tons of other GPG programs on any platform you can think of. Once you turn it on, MailCloak will automatically attach your public key to all outgoing e-mail, and automatically import your friend's public keys when they send theirs to you - so simply send an e-mail to another MailCloak user to begin communicating securely with GPG encrypted e-mail.