I think e-mail changes have for the most part never been done, unless in certain scenarios.
A lot of times what it comes down to is if you own an e-mail account you should always be able to recover it, anyone who wanted to steal an account can claim they weren't able to recover it which is why that isn't really a valid reasoning for wanting an e-mail change.
Using your school e-mail is pretty self explanatory, you know it's going to be deleted eventually and they advise you to not use it for anything non-school related so if you used it for Graal you kinda screwed yourself .
If you just simply prefer another e-mail, setup e-mail forwarding on your old account and have it forward to your new e-mail as I suggested to Losmo but not being able to access your e-mail is something that should have to be fixed with your e-mail provider.