A while back I convinced my cousin to play maple royals, but he didn't have a random email and didn't want to use his business one. I told him I have plenty of extras and he used one of mine. I didn't create the account and he is the only one that plays on it. I know people have been banned for creating account and giving them to family members under the terms that they were "account sharing" because both voted. I want to make sure that I am in the clear before we play anymore.
He can go into the control panel on the main website and change the email attached to his account. It's easy to make a quick Gmail that's his alone. He should also do this himself going forward and not share the email. As for keeping it, I don't know if that breaks any rules, but you know the email, so his account is to some level less secure than it could be.
Thanks for letting me know! I don't really use the email at all so it's not a big deal to me. Well probably just leave it as is unless someone let's us know it's against the rules