"When I’m checking my email, the last thing I want to do is context switch back to the app."

Umm you are signing up for a service, when you click the "register" button, you are usually presented with a message "check your email for a confirmation link" so you go do that. Where is context switching here?

Most of the users don't signup for something and then forget about it until they, by accident, stumble upon the email when they check their inbox the next time. Or am I wrong?