[onethought]

There is no lock in - you can login to "whatever app" and update your email to a new one anytime you like. It's just an email address in the end.

Also, unless you're encrypting your emails, can't everyone read your emails "on the way though" anyway?

[spacedcowboy]

With google, even if you’re encrypting. Gmail, even in the shiny incarnation, only supports server-hosted private keys. A private key that you must give to your service provider is about as useful as a chocolate teapot, imho.