Asia accounts for 42.8 percent of the spam received by Sophos' global spam monitoring network, with North America in second place with 25.6 percent, the company said on Thursday.
Two years ago, North America was responsible for more than half of the world's spam, Sophos said. Now North and South America combined don't come close to Asia's percentage, said Graham Cluley, senior technology consultant at the security provider.
Cluley added that Europe is also becoming a major relayer of spam and now transmits almost as much as North America, with 25 percent. "I won't be surprised if Europe overtakes North America next month," he said.
On a country-by-country basis, the U.S. still relays most spam, with 23.1 percent. China and Hong Kong come second with 21.9 percent of global spam, while South Korea is third at 9.8 percent.
has many computers running older versions of Microsoft Windows, which contributes to the levels of spam, as machines running older versions of the operating system are more easily exploited by spammers.
South Korea is a particularly tempting target for spammers, as a result of its advanced technology infrastructure and the economic rewards of setting up networks of zombie computers, or, Sophos said.
"South Korea has a fantastic Internet structure with immensely fast connections, and so it is a goldmine for spammers wanting to create botnets," Cluley said.
A ZDNet UK research report released this week found that despite advances made in security technology, there has been little or no reduction in the time IT professionals are spending trying to protect their business systems from issues such as spam and viruses.
"The top 10 viruses in the past 10 months are really old, which suggests the human race isn't winning the war against viruses and spam," Cluley said. "Some people just simply aren't bothered, and they are the ones bombarding the rest of us."
However, Cluley said that Microsoft has made some big differences with XP Service Pack 2. The security-themed update to Windows has made it harder for hackers to break into Windows systems, because a rudimentary firewall and automatic updates are enabled by default, he said.
Antivirus company McAfee agreed that security vendors and cybercriminals were locked into a stalemate.
"It's almost like a game of chess," said Greg Day, security analyst at McAfee. "Spammers try to put our customers in check. We put pieces on the board to block them, then they make their next move," he added.
McAfee and Sophos agreed that spam was unlikely to disappear, and called for Internet service providers, businesses and home users to run. ISPs have traditionally been reluctant to block any kind of content, although most of the major players now have some form of antivirus protection for their customers.
"It's an issue we've been working on," Day said. "Every person has to protect their own space. But there's a lot of common sense in moving a security level up into the cloud," or in the space surrounding users and ISPs, Day added.
McAfee and Sophos also applauded the recent arrests of spammers, but said that more needed to be done in terms of international law enforcement cooperation.
"When the prosecutions hit the streets, there was a visible downtrend in spam. But these aren't global laws. It's a step in the right direction, but there's definitely scope to work on this," Day said.
Tom Espiner of ZDNet UK reported from London.