The problem is that all of the people you correspond with use gmail, which participates in PRISM. No amount of transport encryption or storage encryption on your own end will stop Google from sharing that data with US authorities.
The whole protocol and mail delivery system is fucking hopeless.
As an ex-ISP mail architect and ex-operations guy, I hope the whole existing email protocol suite and architecture dies in a fire.
Can the US serve a warrant to a server in Europe run by Europeans? I was assuming the answer was no, in which case you don't need violate any laws or worry about repercussions.