And you are telling us this why?
I guess it's a good (general) warning that if you registered with anything from your gas bill to AW with an old, no longer used email account, it might go AWOL at some point and bugger up your password recoveries, if you don't log in from time to time.
Crikey though, if Microsoft are so short on disk space they can't just cull some of your older mails instead of shutting down your account, I'm not sure I'd want to trust them with anything they store for me.