Spam levels have not returned to their historic highs of early 2010 since a well publicised drop in late December, although the return of prolific spam-sending botnets and the emergence of new networks could keep IT administrators busy, according to Symantec.
The security vendor's January 2011 MessageLabs Intelligence Report revealed that spam now accounts for 78.6 per cent of all email traffic, the lowest rate since March 2009 and a drop of 65.9 per cent from a year ago.
The fall is mainly down to a two-week period from 25 December to 1 January when spam fell 58 per cent from 80.2 billion emails a day to 33.5 billion, a similar drop to that seen when the McColo network was shut down in 2008, Symantec said.
The closure of spam affiliate Spamit was partially responsible for the disruption to spam output, but the decline may not last for long, according to MessageLabs Intelligence senior analyst Paul Wood.
"There are likely to be other factors at work, such as consolidation and restructuring of pharmaceutical spam operations, which have led to instability in the market likely to be exploited as a business opportunity by other spam gangs," he explained.
"We expect to see more pharmaceutical spam in 2011 as new brands emerge and botnets compete for their business."
Rustock, the key spam-sending botnet which had been responsible for 47.5 per cent of all junk mail, is back online but sending spam at lower levels than before.
However, others, such as the Bagle botnet, are already moving in to take its place, said Symantec.
The news comes just one week after Cisco declared that 2010 had seen the tide turn against the spammers following a 90 per cent fall in levels of unwanted mail.
Cisco senior security researcher Henry Stern told V3.co.uk that the problem of spam could be "considerably reduced" if law enforcers continue to concentrate on shutting down affiliate programmes.
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