I too am unable to sign in to one of my Outlook accounts.
I am not getting any error message but it's telling me that my account doesn't exist.
I checked and found that many others are reporting the same.
Yeah, everyone is getting it. Their servers are down completely. My live email account doesn't exist apparently and my Xbox is having a period. Can't even chat to support because they ask you to log in first.
yeah, its odd that i can't find many articles about it. only a couple from the UK seem to be reporting on it, plus a post in reddit. surprised windowscentral hasn't commented on it yet. it's been going on for over an hour at least, if not longer.