I've currently got my e-mail hosted at iCloud, but I don't use the icloud e-mail address. My public e-mail address is a forwarding service which simply redirects to wherever I tell it to, in this case ...

gpg-mailgate is a small content filter for Postfix + web interface that allows any user to upload PGP keys to your server (and confirm email address), and then will begin encrypting any outgoing mail ...