When you get a spam message you probably think it came from some far away country. Russia perhaps, or maybe China. With the CAN-SPAM act many people assume spammers here in the U.S. don't have a chance. Wrong! According to a report released by security firm Sophos, the country sending the most spam is the good old United States. We lead the pack, responsible for 28.4 percent of all spam sent worldwide. South Korea was a distant second at 5.2 percent, followed by China and Russia.

"It seems as though a major American spammer is arrested every other week at the moment but, despite these high-profile law-breakers being put away, the U.S. continues to relay far more spam than any other nation on the planet," Carole Theriault, senior security consultant at Sophos, said in a statement.

"This level of activity can't be attributed solely to the slick operations of a few cash-hungry criminals. The problem is there are thousands of spammers using many thousands of compromised zombie computers in the U.S.," Theriault said.

"The only way we're going to reduce the problem is if U.S. authorities invest a lot more in educating computer users of the dangers, while ensuring ISPs step up their monitoring efforts to identify these compromised machines as early as possible," added Theriault.