Internet trends watcher MessageLabs reports that spam traffic on the Web dropped by more than 80 per cent just 12 hours after the closing of a major spam hosting operation. But that trend may not last.

McColo, a San José, CA, based Web hosting company known to harbour spammers, closed its doors this past Tuesday, largely as a result of investigative reporting by Washington Post Computer Security correspondent Brian Krebs.

Krebs and professional Internet watchers gathered information on McColo for months before acting. By early this month, it had become clear to investigators that McColo hosting clients were responsible for at least 75 per cent of the spam bombarding global e-mail users.

This past Monday, investigators contacted McColo’s upstream network providers, who — on hearing the evidence — cut off McColo’s access to the Internet.

Investigators warn that, while McColo is gone, the spammers are not. In fact, veteran Web watchers predict that the spammers and possibly McColo itself, will simply relocate to Eastern Europe, where commerce and the Internet are largely unregulated.