PM sentMicrosoft isn't using it, they're referencing Snattlerake's hotmail account. Microsoft has owned hotmail for a good 25 years now; although it has been replaced by outlook.com, the old hotmail addresses are still valid.
I have seen messages from Microsoft that look very much like that, and I'm pretty sure I've seen that one regarding my work account. As to whether or not it's legit, it depends on what you were doing when it popped up. IIRC, when I saw it was while I was logging into my Microsoft365 account at work, and it was a legit message then.