Spam born in the USA - and much is porn

The vast majority of spam originates in the US and this summer, like last, much of it is pornographic in nature.

Nearly 86 per cent of all spam messages sent since May 2004 came from the US, according to email security firm CipherTrust. This indicates spammers are finding ways around that country's anti-spam legislation.

US spam-sending computers have been quite busy, as just 28 per cent of IP addresses used to send spam are located in the country.

By contrast, Korea also accounts for 28 per cent of IP addresses used to send spam but these machines send only three per cent of the total volume of junk emails.

The other major spam-senders, China and Hong Kong, are the location for 23 per cent of the IP addresses and send about 2.6 per cent of the worldwide volume.

The UK barely registers in both areas, accounting for just 0.21 per cent of the total spam volume and 0.54 per cent of the IP addresses.

One way spammers are thwarting CAN-SPAM, the US anti-spam legislation, is by requesting that recipients unsubscribe to messages via the post. The law stipulates that all legitimate messages must offer a way to unsubscribe, but doing this through the post makes the process time-consuming and thus violates the spirit of the law.

Paul Judge, CTO at CipherTrust, says the company's research also shows that relatively few people - around 200 - are sending the world's spam.

A separate report from security firm Clearswift shows a spike in the amount of pornographic spam messages sent this summer - since June, the figure's up 350 per cent. Traditionally messages selling cheap software, mortgage deals or prescription drugs are more common than porn spam, though a rise in the levels of the latter occurred last summer as well.

CipherTrust's data comes from analysing messages collected from the nearly 2,000 enterprises using the company's IronMail email security appliance, while Clearswift's figures come from examining messages arriving at the company's many seed accounts.