In the spirit of entrepreneurship, spammers are finding new ways to send out their junk mail just weeks after the shutdown of a major web-hosting firm took many of them off the map.According to Message Labs, a division of Symantec, after Web-hosting company McColo Corp. was shut down two weeks ago, spam levels declined by 65 percent. Now new analysis finds spam levels are returning to two-thirds of what they were before the McColo Corp. takedown. McColo played host to several massive spam-sending botnets and its shutdown caused spam levels to plummet because the spammers were out of business. The lag between the initial decline and the subsequent rise is attributed to the time it took for the botnet owners to find a new ISP and bandwidth provider, according to Matt Sergeant, Senior Anti-Spam Technologist at MessageLabs."The Asprox and Rustock botnets are back with a vengeance after having found new command and control," Sergeant said in a statement. "Cutwail never went away and it seems its owners have used the opportunity to increase output. Mega-D is also on the rise again, he said. Srizbi, having once been responsible for 50 percent of all spam, is now completely defunct. Without this botnet, spam levels won't return to what they had been." The research conflicts with figures from messaging security firm IronPort, which is part of Cisco Systems. The company claims to have blocked approximately 35 million spam e-mails on Monday, which is far below the level of blocking it saw before the McColo takedown. Ironport claims to have blocked in excess of 150 million spam messages before McColo's demise.Message Labs' Sergeant urged vigilance in the face of the news."As always, businesses and consumers are urged to make sure their spam filters and anti-virus engines are up to date."