Encrypted emails - Expert opinions needed

[Bigfoot]

Sorry if this is the wrong forum for this, but I couldnt find one that seemed like a better place. Anyway I'm in need of an encrypted email service and I honestly have no idea where to even begin. Basically the purpose of the account is that I need to be able to send and receive confidential legal documents.

What I found so far are:

http://www.canadapost.ca/personal/of.../default-e.asp

http://www.ziplip.com/products/ZLSecureMessaging.html

https://www.hushmail.com/

The Canada Post service is the "safest" bet in that it's security is guaranteed by the Canada Post Act, but it's also very expensive relative to other options. The high cost is actually prohibitive, and I really need another option.

Are either of the other comparable to the Canada Post service? or are they not nearly as secure. I'm clueless as to how they differ and it's important that whatever option I choose is secure because of the fact it will be confidential legal documents that I'm transferring. Thanks to anyone who can shed some light on this subject for me.