Despite getting only one response for every 12.5 million messages they send, spammers are able to turn a profit and remain undeterred. E-mail users have received a brief respite, however, after two US internet service providers disconnected the service of McColo Corp., a Web hosting service that may have been responsible for as much as 75% of spam sent worldwide. One anti-spam firm reported a 70% drop in junk mail levels since McColo was taken offline nearly a week ago, but spam levels will likely rebound quickly, as networks move from North America to areas with less scrutiny.