Anyone who has used e-mail for anything other than writing to their spinster aunt has probably received scam letters of various sorts as a result. Unfortunately some of the more naive and/or greedy recipients of these e-mails have lost money, or even ended up in physical danger when they've been taken in. But not surprisingly there has been a counterreaction. Some folks turn the tables, and screw over the scammers by making them waste time, effort, and if they're lucky money, trying to scam them. You can read about some of the activities of these antiscammers here.