One in ten websites send spam email, says Spam Ratings.
The spam research firm revealed spam created by websites has risen by 110 percent since October last year. Furthermore, one in five websites automatically opt-in consumers when it comes to sharing their details with third-parties, despite the fact its breaches email marketing best practice.
Two in five of spam emails that contain malware feature pharmaceutical or sex-related content, while 35 percent are related to finance and 15 percent are phishing emails that impersonate bona fide sites in a bid to steal log-in details.
Three-quarters of emails from the UK's top 10,000 websites are either unwanted, nuisance or dangerous spam emails.
"Spam is a nasty and dangerous disease that has turned into an epidemic in the UK," said Andy Yates, co-founder of Spam Ratings.
"Websites are the main cause and the main way the disease has spread. Too many websites sell data to third parties and are the source of the huge growth in unwanted and dangerous emails. "
Yates urged consumers to web users to be when shopping online or signing up to websites.
The research firm has also started a Stop Spam Abuse campaign on Facebook.
"Any websites mentioned on our Facebook 'wall of shame' will be investigated and, if appropriate, reported to the appropriate trade or law enforcement body," Yates said.
See also: 51% of firms send unwanted spam emails