Microsoft will begin offering its first hosted security service under the Forefront brand on Thursday, dubbed Forefront Online Security for Exchange and designed to help keep malware and spam out of e-mail in-boxes.

The hosted service, which will cost $20 per user per year or less based on volume licensing, targets enterprise Exchange customers and includes a Web-based console for setting up policies for virus and spam protection, said Doug Leland, general manager of Microsoft's Identity and S...