It's partly legit. If they did send a legal actions letter it'd be in your in-game message box although it's most likely a bluff on their end seeing as no reports of any individual bot users being sued or anything has come up.
All emails are fake or some sort of spam now days
TBH I wouldnt even go on your email if your already getting those I know I dont go on mine unless I'm looking for something I know is real like a password confirmation reset thing