some viruses you can't tell who sent them unless you're some sort of government inteligence tracker. i'm assuming you got a email worm the header is probably faked by it and also some of the newer worms can fake the smtp info. so you might not be able to tell who sent it.
Did a virus checker pick it up? Also install IE 6 and ALL updates. This will prevent outlook from opening bad MAME headers. Also some users try to fake the Gens team. Trust me... normally I dont use "Mysticales" as the "From" list, sometimes, but id never send a file period... if I did it would be from my darkmystics email as its faster.
no clue how to rid your system of it what antivirus do you use if it doesn't detect it and remove it send it to them. i can only tell you how to send it to norton's. I forgot to mention before some worms have their own SMTP so they can send themselves out to people.