I recently got a bulk of sobig into my yahoo accounts. The from addresses seemed to be known by me. Infact they were of my college friends. Now when I read about the worm on symantec they said it was a mass mailing worm and used the cookies stored on the pc and uses smtp. But we have norton installed on all pcs so all outgoing smtp mails are scanned but i have never noticed any one from this virus..
So if any one knows how this worm works exactly please let me know....