Why don't you use email encryption?
smanek: I think the key problem (no pun intended) is that email encryption can't be securely implemented on the server side.Simply put, most of the people who are paranoid enough to need email encryption don't trust Google (GMail) with their PGP private keys. Therefore, they either have to use an offline email client (unacceptable to a lot of people) or install a brittle and poorly integrated third-party solution like FireGPG (which the vast majority of users will never do).