nice thing with most mail hosts is they can block a hell of a lot of crap right at their box, but in a case like this there's not a lot of hope, really. especially since it's a microsoft mail server, and hotmail nonetheless.
if it is a spammer, good luck catching them. they are pretty smart these days, it's fairly difficult to catch a good spammer.
hopefully it's just the virus. i know a lot of isp's were _insanely_ busy blocking off the latest virus.. basically blocking attachments and such. they were having their systems block thousands of these emails an hour. that totally sucked, there was a lot of shit flying around.