Microsoft is to buy antivirus and anti-spam company Sybari Software to provide its enterprise customers with improved ways to protect against malicious software.

Mike Nash, corporate vice president of the security business and technology unit at Microsoft, said that the acquisition will provide customers with a server-level antivirus offering that delivers file and content filtering capabilities, as well as the ability to use multiple scan engines.

Nash added that enterprise customers could deploy a single Sybari product to work with multiple versions of Microsoft Exchange and Lotus Notes.

According to Microsoft, email attachments are the means of infection in 88 per cent of virus incidents in corporate environments, creating "a clear indication that further innovation is required".

The terms of the deal were not announced, and Sybari will maintain all current operations until the acquisition receives regulatory approval.

Last year Microsoft bought Giant Company Software, a developer of anti-spyware and internet security offerings.