Account appeal

Hello i am writing here on behalf of a IRL friend of mine, who got his phone stolen and on it was the Google Two-factor authentication app for his Warmane account. His account is very old and he doesn't even remember the email it was signed on. The account is premium, he has invested a lot of time in it, he has several characters in both Icecrown and Outland, so he, me and our Outland raiding guild <Marbles> would very much like to recover it.
He knows the username, password and names and info about all the chars in the account.
Me and the members of <Marbles> can confirm that he is in-fact the owner of the account.
We know it's his fault for being so careless about...well pretty much everything, but if you could help us it would be very much appreciated.