If you've noticed a spike in the amount of spam you're receiving, you're not alone. According to an analysis by Google, the volume of junk mail has returned to levels not seen since November, when host provider McColo was disconnected.
By the second half of March, spam volumes returned to pre-McColo takedown levels, according to the analysis, which was based on the inboxes Google manages for more than 50,000 businesses and 15 million business users. What's more, the growth rate during the first quarter of this year, at 1.2 percent per day, was the highest it's been since early 2008.
"It's difficult to ascertain exactly how spammers have rebuilt in the wake of McColo, but data suggests they're adopting new strategies to avoid a McColo-type takedown from occurring again," Amanda Kleha, a member of Google's security and archiving team, writes here. "Specifically, the recent upward trajectory of spam could indicate that spammers are building botnets that are more robust but send less volume – or at least that they haven't enabled their botnets to run at full capacity because they're wary of exposing a new ISP as a target."
Spam levels plummeted following the mid-November takedown of McColo, which hosted the master control channels for some of the world's biggest and most notorious spam gangs. McColo's ouster came after its upstream providers pulled the plug on their customer following complaints it was a conduit for junk email, phishing, and other types of online crime. Almost overnight, spam volumes dropped by 40 percent or more, by some estimates.
Since then, spam levels have slowly crept upward. In January, web-filtering firm MessageLabs reported that spam volumes were about 80 percent of pre-McColo takedown levels.
Additionally, over the past month Google employees have observed a rise in the amount of spam with malware attached. They've also seen new scams that target recipients by their geographic location. ®