Probably nothing cause YouTube never listens to those even if it is your material.
To be fair, I have actually successfully disputed and appealed third party claims for the use of royalty-free production music . . . unfortunately, the process lasted all the way up to the last minute of the timeframe the police company that issued the claim were supposed to respond, but luckily I got the claims removed.
But that being said . . . yeah, when it comes to something you don't even own or don't have permission to upload, there's really sense in trying to appeal.
So . . . about that email?