The US is the biggest spammer, despite efforts to combat unwanted e-mail, according to net security experts.
Most spam blighting inboxes is from the US
Almost 43% of all unwanted e-mails originated from the US in the last month, said anti-virus firm Sophos.
The report suggests that anti-spam laws passed in the US nine months ago have had little impact.
South Korea, the most broadband-connected country in the world, was next in line, firing out 15% of all junk e-mails.
"Almost nine months on from the Can-Spam legislation and the US's attempt to clean up its act appears to have had little impact," Graham Cluley, senior technology consultant for Sophos said.
"Canada has made some progress, however, cutting the percentage of the world's junk e-mail sent from the country by over half, from 6.8% six months ago to 2.9% today."
The figures also showed that South Korea had tripled the amount of spam mails sent out from its networks since February.
The Can-Spam Act (Controlling the Assault of Non-Solicited Pornography and Marketing) was passed by US law-makers in late 2003 and came into force in January this year.
It means spammers can be imprisoned and it also outlaws many of the tactics they use to hide their tracks.
TOP SPAM NATIONS
1 - United States 42.53%
2 - South Korea 15.42%
3 - China (& Hong Kong) 11.62%
4 - Brazil 6.17%
5 - Canada 2.91%
6 - Japan 2.87%
7 - Germany 1.28%
8 - France 1.24%
9 - Spain 1.16%
10 - United Kingdom 1.15%
11 - Mexico 0.98%
12 - Taiwan 0.91%
Source: Sophos August 2004
It also requires that unsolicited e-mails should include a way for recipients to "opt-out" of receiving future e-mails.
Only net service providers and governments can use the Can-Spam Act to tackle spammers.
In March, AOL, Microsoft, Earthlink and Yahoo filed lawsuits against individuals in the US who they claimed used open proxies to send spam through innocent third-parties and used false "from" e-mail addresses.
"Spammers are motivated by watching their bank accounts get fatter and fatter, and many have turned to hacking into innocent third-party computers to send their junk emails," Mr Cluley commented.
"Many of the computers sending out spam are likely to have had their broadband internet connections exploited by remote hackers."
About 40% of global spam is sent out via "zombie computers", machines which have been harnessed without the knowledge of the PC user, he added.