So this happened to a friend of mine maybe 6 months ago - he did get his account back
i did some research into this at the time, a lot of forums/reddit and the like
i know
@alasdair said it, but im not sure if
@Lexkalin confirmed it.
in the majority of these "sudden bans" they are all accounts that use msn/live email accounts, i didnt find too many people that didnt have (at)hotmail/msn/live or other primary microsoft domains included.
my friend did get his account back, and microsoft seemed to insinuate at the time that it wasnt a"xbox" TOS that had been breached.
ive not looked at it for months, but i would ask people elsewhere if they are registed using a MS domain