The research by anti-virus company Sophos found that the level of non-English spam has risen, with the vast majority now being relayed by "zombie" computers hijacked by trojan horses, worms and viruses under the control of hackers.
Sizeable increases are also happening in "pump-and-dump" stock spam, designed to inflate stock prices artificially before spammers sell shares at a profit.
The top spam-relaying country was the U.S. with 24.5 percent of the world's share, followed by China at 22.3 percent. South Korea finished third with 9.7 percent.
Legislation such as CAN-SPAM and greater information sharing by ISPs has led to severe penalties and fines for those found guilty of spamming. Recently, an Iowa-based ISP was awarded $11 billion in a judgment against Florida-based spammer James McCalla, while another culprit, Daniel Lin of Detroit, is currently facing a sentence of at least two years imprisonment for his actions.
"It's good news for the U.S. - the tougher sentences being dished out are clearly making spammers feel the heat," said Graham Cluley, senior technology consultant at Sophos. "However, it's not such good news for Bill Gates's skills as a fortune teller, as spam is clearly not a thing of the past. Email users worldwide are still being bombarded by all manner of unsolicited messages, and it must be said that, two years on, Gates' famous prediction now looks extraordinarily optimistic."
Similar sentiments were echoed across the industry. Mark Hanvey, chief security officer at Cable & Wireless, said that in a way the prediction has come true, but "sadly though it has returned in a more threatening zombie form."
"We no longer see spam issuing from one central mailbox, instead we see viruses that hijack innocent computers and create an army of zombies sending out emails on the spammers behalf," said Hanvey.
He warned that with the advent of internet telephony, spammers were preparing to deluge people with voice spam.
"The tipping point will be reached this year where the effort and expertise to create voice spam will be outweighed by the potential audience," said Hanvey.
He said there was little legal protection afforded to ordinary consumers in the U.K. caught up in spam.
"The Computer Misuse Act is 15 years old and is out of touch with the realities of computer crime. The act was passed long before the arrival of denial of service attacks, or the broadband networks over which they run," said Hanvey.
Scott Chasin, chief technology officer at MX Logic, said delivery methods for spam emails have changed since Gates made his prediction.
"Versus two years ago, spam is largely being delivered from hijacked PCs," he said.