The United States, Canada, China, South Korea and the Netherlands are the top five birthplaces of spam worldwide, according to a new analysis by security software maker Sophos.
In an analysis of junk e-mails received over two days in mid-February, the company created a list of the "dirty dozen" spam-producing countries.
Taking the undisputed helm on its list of spam-producing countries is the United States, which accounted for more than half of the world's unsolicited e-mail at 56.7 percent during the period of study.
Canada accounted for 6.8 percent; China, 6.2 percent; South Korea, 5.8 percent; and the Netherlands, 2.1 percent.
The other top 12 countries were Brazil, German, France, United Kingdom, Australia, Mexico and Spain. However, those seven countries in total accounted for just more than 10 percent of all spam.
All other countries in the world created an additional 12.2 percent of the globe's spam.
"The United States is far and away the worst offender, accounting for nearly 60 percent of the world's spam. Even though European countries are responsible for less spam, they are still generating millions of junk e-mails a day," Graham Cluley, senior technology consultant at Sophos, said in a statement.
The list may not be a completely accurate reflection of spam's origins, Cluley acknowledges.
"Our intelligence suggests that a large amount of spam originates in Russia, even though it appears at only No. 28 in the chart. Hackers appear to be breaking into computers in other countries and sending out spam via infected PCs," he said.
Charles Cousins, managing director of Sophos Asia, noted that hackers are relentlessly breaking into computers of unsuspecting owners in other countries via methods such as worms and Trojan horses.
Sophos estimates more than 30 percent of the world's spam is sent from infected computers.
Zen Lee of CNETAsia reported from Singapore.