The Q2 2010 report from Sophos shows that the US generated 15.2% of all global spam messages – an increase from 13.1% in the first quarter of the year.

The UK, meanwhile, which actually dropped off the spam hall of shame last year, also saw a significant rise in the proportion of spam servers in the UK. With a total output of 4.6% of the world's spam, the report says this puts the UK in fourth place overall.

Sophos is also warning that spam is becoming increasingly malicious – not just advertising unwanted goods, but spreading links to malicious websites and computer-infecting malware.

Graham Cluley, Sophos' senior technology consultant, said that it is sad to see spam relayed via compromised European computers on the rise. "The UK, France, Italy and Poland have all crept up the rankings since the start of the year", he noted.

"Financially-motivated criminals are controlling compromised zombie computers to not just launch spam campaigns, but also to steal identity and bank account information", he said.

According to Cluley, spam will continue to be a global problem for as long as it makes money for the spammers.

To combat the spammers, Cluley added that it's not only essential for computer users to run up-to-date security software, "they must also resist the urge to purchase products advertised by spam".

Infosecurity notes that most internet users are unaware of the enormity of the spam problem, as tier one ISPs are now filtering out spam on their own platforms, because if all emails were sent to users, the data download implications would be significant.