Microsoft said Tuesday that it is buying Sybari Software , an anti-virus and anti-spam software company. The terms of the deal were not disclosed.

Microsoft intends to use the acquisition to provide its corporate customers with technology to protect themselves against malicious software, according to a company statement. The acquisition is Microsoft's first in the anti-virus market since the company purchased technology from GeCAD Software of Bucharest, Romania, in June 2003. It also comes amid expectations among industry insiders that company Chairman and Chief Software Architect Bill Gates will use a keynote speech at next week's RSA Security Conference in San Francisco to announce plans for a consumer anti-virus product.

Sybari, of East Northport, N.Y., makes anti-virus, anti-spam and e-mail content filtering products for big companies. Sybari's Antigen anti-virus product is server-based and uses multiple anti-virus engines to scan e-mail messages for viruses.

Microsoft began negotiating with Sybari, a private company, around one month ago, said Mike Nash, vice president of Microsoft's Security Business and Technology Unit. Sybari was considering an initial public offering before Microsoft agreed to buy it. Microsoft was prompted by customer demand for more anti-virus protection on Exchange servers, Nash said.

Sybari gives customers a choice of anti-virus engines from companies such as Sophos, Computer Associates and Kaspersky Labs, but the company does not have its own anti-virus engine. Sybari works with Microsoft Exchange e-mail server, as well as Microsoft Office SharePoint Portal Server 2003 and Microsoft Windows SharePoint Services, which are used to manage and share documents and information across an organization.

The purchase is not surprising, considering Sybari's strength on Microsoft Exchange and the two companies' close business ties, said Brian Burke, an analyst at market-research company IDC. In fact, Microsoft commonly recommended Sybari to customers looking for an anti-virus product that works with Exchange, Burke said.

Sybari's use of other companies' engines also stays true to Microsoft promises to avoid domination of the anti-virus software market and play fair with other anti-virus companies, Burke said.

The IDG News Service is a Network World affiliate.