On the first anniversary of the McColo shutdown, spam levels have more than recovered, according to experts.

Recent figures released by security firm McAfee indicate that spam levels are at an all-time high.

When the notorious hosting provider was shut down in November 2008, spam levels immediately plummeted. Though experts were sceptical that the shutdown would deal a lasting blow to spammers, there was hope that levels would at least drop slightly.

According to McAfee threat management director Sam Masiello, spammers have recovered even faster than expected, and spam levels are continuing to climb with the help of several new massive botnet infections.

"Not only did spam volumes recover, unfortunately, but they recovered quickly and have greatly surpassed the volumes that we saw before McColo was taken offline," Masiello wrote in a blog posting.

"Spam volumes have more than doubled since just Feruary 2009, dwarfing several times over the decreases due to McColo’s demise."

On the anniversary of the bust, news has surfaced of another botnet takedown. Researchers at MessageLabs are reporting that security experts have managed to cripple Mega-D, a massive botnet that had been a major contributor to global spam loads.

If the McColo takedown has taught security researchers anything, however, it is that spam drops from takedowns such as Mega-D will likely be short-lived.

Masiello suggested that McColo's takedown could have a more lasting effect on the management of botnets. He explained that in the wake of the takedown, botnet operators began spreading out their control operations across a number of networks rather than rely on a single host.

"McColo has taught botnet owners a lesson," Masiello wrote.

"Today taking down a big hosting provider would prove only a minor inconvenience as opposed to a major victory for security forces."