Spam email messages have fallen by eight per cent thanks to the demise on 20 September of California-based ISP Intercage, according to security vendor MessageLabs.

A team of cybercrime experts published a white paper last month which suggested that 78 per cent of the domains and mail servers on Intercage's network were hostile.

The ISP has since been knocked offline, causing a drop in global spam. But the dip is not expected to last long, according to Mark Sunner, chief security analyst at MessageLabs.

"Addresses on Intercage's network range were being used to host command and control channels for botnets," he explained.

"In disrupting these botnets, the level of spam activity towards the end of September was severely impaired. But we do not expect this dip to last long.

"This time of year is notorious for increased levels of spam activity as spammers ramp up for the holiday season."

The global ratio of spam in email traffic throughout September fell to 70.1 per cent, or one in 1.43 emails, a decrease of 8.1 per cent on the previous month.

But the same period saw an increase of .16 per cent in the proportion of phishing attacks compared with the previous month. One in 288.1 emails (0.35 per cent) comprised some form of phishing attack.

Email borne virus levels for Q3 2008 are at their highest level since Q3 2007 and at similar levels to Q3 2006 accounting for one in 131.7 emails.