is this e-mail Legit?

The e-mail address, einquiry@nexon.net, which is indeed Nexon's e-mail address (for game questions, atleast) proves that it's legit. Grats on winning. (Even if the e-mail name was faked, where's the harm in giving an ID? Can you use a mule account as the ID?)

I believe that there was a certain exploit a while ago where you can apparently hack someone's account by knowing the login ID and one more thing, which I think is the birthdate. (Can anyone confirm this?)