I've been having a problem using gmail in my Mail app for sometime now. I have 2 step verification turned on, and every couple of weeks I can't send any emails. Receiving emails works fine. It could be more frequent, but I don't send emails from my MBP that often, I usually send from other devices. The mail app is telling me that I have to re-enter my password. Entering the correct app specific password doesn't work. I have to go into gmail on the web, revoke access from my MBP and then regenerate a new app specific password. Has anyone encountered this, or know a work around? This has only started happening once I upgraded to Maverick.