> You lose it by exposing it to a third party

It's true that this has always been the position of the Federal government, but that argument has always seemed pretty weak to me, and I don't accept it on principle, no matter how pervasive it's become. People don't expect their email to be read by others, especially the government, period. The reality that they are in fact doing this anyway just means citizens have to push harder to affect a change in the law.

This isn't a new fight. The government literally used the same exact argument when telephones were invented. It took years to work in protections for phone calls, I see no reason why the same can't be done for new modes of communications like email.