6 .Microsoft Business Productivity Online Suite (BPOS):

Microsoft Business Productivity Online Standard Suite is a messaging and collaboration tool, which is delivered as a subscription service. It also includes Microsoft Exchange Online for email and calendaring; Microsoft SharePoint Online for portals and document sharing; Microsoft Office Communications Online for presence availability, instant messaging, and peer to peer audio calls; and Office Live Meeting for web and video conferencing describes the Product Overview.

This was a product to compete with Google Apps. All these were based on cloud and were known as the cloud apps. But the downside of the suite was, it did not have Microsoft's most popular Office apps, Word, PowerPoint, Excel. Knowing their drawbacks, Microsoft then came up with the improved version of BPOS, Office 365. Office 365 has all the cloud based versions of the office apps. But BPOS users could not be easily migrated to it. It was too complex and took a very tedious long process for the conversion.