hardware appliance to encrypt email?

Hi,
I've been wondering if there is a hardware appliance that could be connected between an email server and the proxy server that would encrypt all outgoing email and decrypt all incoming email.
I know there are software programs. I thinkI'm getting a little tired of having to update my applications and server OS whenever I need to add funcionality. Also, an appliance would keep me from adding more of a load to the servers.

bob kahler
rkahler@pixley.com