This is called a "Nigerian scam". I got hit with it when I tried to sell my radio on Ebay last month. The [censored] put in a winning bid of $350, then said he'd send a cashier's check for $500 and wanted me to send him back $150; said a friend of his in the area would come pick up the radio. When I asked for his friend's name, address, and phone number, his stream of email abruptly stopped. That same guy created a new ID each day on Ebay, then bid/won hundreds of auctions per day, mostly high-dollar items like cars and motorcycles. Then he contacted the sellers with his scam.

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