Microsoft last week announced its intent to acquire FrontBridge Technologies, a provider of online service for securing and archiving e-mail.

Microsoft plans to continue running the company and offering a service to provide corporate users with archiving features targeted at e-mail disaster recovery, as well as compliance, spam and virus protection.

Terms of the deal were not announced, but Microsoft said all 160 employees of FrontBridge, headquartered in Marina Del Rey, Calif., would stay on with Microsoft.

"It's a good move for Microsoft," says Matt Cain, an analyst with Gartner. "It highlights the increasing [corporate] demand for e-mail hygiene services and the growing demand for this delivery model."

The deal comes almost five months after Microsoft acquired Sybari Software and its anti-virus and anti-spam products. Cain says Microsoft now has two of the three methods for delivering e-mail hygiene: hosted (FrontBridge) and premise (Sybari). Microsoft lacks an appliance.

Postini and Message Labs are the other two major providers offering e-mail security as a service over the Internet.