Sophos' Richard Wang reports that, between December 2012 and February 2013, the U.S. led as the world's leading spam-relaying country. According to Sophos' statistics, the U.S. was responsible for 18.3 percent of all spam, with China in second place at 8.2 percent.

"Back in October, the U.S. occupied the third position with only 6.5 percent," writes Softpedia's Eduard Kovacs. "At the time, India was the leader with 16.1 percent, but now India has dropped to the third place with only 4.2 percent."

"Aggregating the countries by continent, though, does offer a different view," The H Security reports. "While there has been a swing of 12 percent from Asia to North America, Asia maintains the top spot at 36.6 percent followed by Europe at 27.5 percent, North America at 22 percent, South America at 10.9 percent and Africa at 2.6 percent."

"All this being said, this does not mean that the spammers themselves have migrated west -- only that they've just recently had an easier time compromising computers in the U.S.," Sophos' Wang writes.