The volume of junk e-mail, or "spam", has exploded more than 25-fold since the beginning of the year, and now makes up 1 e-mail in 8 received in Britain.
Tracking by MessageLabs, an e-mail security company, has found that the number has grown from barely 1 in 200 e-mails at the start of the year. But the problem is even worse in America, where it has grown from 1 in 37 e-mails (about 2.7 per cent) in January to 1 in 3, or 33 per cent, today. And Mark Sunner, the chief technical officer at the company, said: "The situation will only deteriorate in the future."
The deluge of spam e-mails offers anything from health and financial products of dubious value, through pyramid and organised crime scams, to links to pornographic and other sites. Its growth had been helped by CDs with millions of e-mail addresses grabbed from the Web and programs that made it simple to send out millions of messages at once, said Neil Hammerton, of EMF Systems, which offers spam-filtering services to internet service providers (ISPs), companies and individuals.
"It's become more devious," Mr Hammerton said. "The programs that spammers use can fake who they're from, and the subject line and sender's name will be subtly different with each e-mail. That makes it incredibly hard to block."
Of the 30 billion e-mails daily, so many are now spam that they are putting a strain on ISPs' mail servers as they try to pass them on.