Can't the original owner find a way to recall the account? Saying he was hacked.
Edit: I just remembered reading an article [1] about hooking up a regular gmail account to the free tier of mailgun, so you send and receive through your custom domain but otherwise have a plain old gmail account.
[1] https://simplyian.com/2015/01/07/Hacking-GMail-to-use-custom...
wow, this is really a thing.
It'll never be used but I'm glad I can say I have it.
(edit: what I mean is that he can recall the account and get full access to it while DNS still points to Google)