A web hosting firm that apparently sent out more than 75 per cent of worldwide spam has been knocked offline.


Following reports from Security Fix on evidence gathered about criminal activity emanating from the network, McColo has been switched off following claims that its client list includes some of the most disreputable cyber-criminal gangs in business today.


On Monday, Security Fix contacted the internet providers that manage more than 90 per cent of the company's connection to the larger internet and sent information about activities at McColo, as documented by the security industry.


Jason Steer, spokesperson for Cisco/Ironport, said: “It started with finding the people who hosted networks that sent spam and within seconds of it being turned off the amount of spam being sent had dropped.


“We know that over 200 billion spam messages were sent every day before this, and after it was switched off we thought there was a problem with the system because of a drop in spam.


“This botnet has been well known for a while as the criminals had been able to set up a legitimate business at the front end, and if the police were to ask them about it they can say that ‘it was one of our customers that did it and it wasn't our problem'.


“I think that this will lead to a temporary lull as the amount of money made is significant, so I expect that there will be a drop in the amount of spam for a week or two but we won't see this lasting for a long time.”