Antispam firm Cloudmark nabs $4.5 million

Cloudmark, which makes software that filters unsolicited commercial e-mail, on Monday said it raised $4.5 million from Ignition Partners, an investment firm founded by former Microsoft executives. San Mateo, Calif.-based Cloudmark produces SpamNet, a spam-fighting tool that identifies junk e-mail and quickly updates e-mail filters by harnessing the intelligence of the Web community.

The year-old product is based on Razor, an open-source spam-filtering system that sifts out junk mail on the advice of nearly 500,000 users. Cloudmark also sells Authority, a filtering software aimed at corporations.