The UK has jumped from ninth to fourth place in the ranking of spam-relaying countries since the first quarter of the year.
The UK relays 4.6% of all global spam messages, according to spam report for the second quarter of 2010 by security firm Sophos.
The US continues to be the number one spam polluter, pushing out 15.2% of all spam, up from 13.1% in the first quarter.
"It's 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," said Graham Cluley, senior technology consultant at Sophos.
Europe tops the list of spam-relaying continents, accounting for 35% of all spam, followed by Asia (30.9%), North America (18.9%), South America (11.5%) and Africa (2.5%).
Financially-motivated criminals are controlling compromised zombie computers to not just launch spam campaigns, but also to steal identity and bank account information, said Cluley.
"Businesses and computer users must take a more proactive approach to spam filtering and IT security in order to avoid adding to this global problem," he said.
Spam e-mails make up 97% of all e-mails received by business e-mail servers, both putting a strain on network resources and wasting a huge amount of time to lost productivity, the Sophos report said.
The best way for users and administrators to reduce the risk of being compromised is to run anti-spam and anti-malware protection, behave sensibly when online, and ensure their systems are up-to-date with security patches, the report said.
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