Comment by jonathanlydall

I always thought of outlook.com as a rebranding of Hotmail (which itself had been continually evolving, was probably actually “Live” at that point), I would expect it is the same (ever evolving) infrastructure.

In which case, people like me with an @hotmail.com address from the 90’s were much earlier users of the outlook.com email boxes than when the domain was “launched” by Microsoft.