Answer by Doug S. for Is email encryption practical enough?

Another option is Voltage SecureMail. It uses Voltage IBE (Identity Based Encryption), which is considered the next generation of PKI that doesn't require certificates for the public key...just an email address.

Voltage SecureMail has Outlook plug-ins or a web interface for sending encrypted email. Messages are completely controlled by the sender and recipient. No messages are stored on servers.

Recipients don't need any special software to decrypt and read their messages. It's much easier to use than PGP or SMIME and just as secure.

Try it at: www.voltage.com/vsn