Outlook and MAPI providers

Although BCM shows up in Outlook, and is well integrated in the user interface, there's a important distinction between the two.

The Outlook program is a user interface for data stores and messaging systems - both types of MAPI providers - and Outlook can host multiple MAPI providers. In your Outlook folder view you may see several top level nodes: Mailbox, Archives, Public Folders, SharePoint Lists, Business Contact Manager, etc. Each of those is a different MAPI store. Because some program (e.g. Outlook Connector, ActiveSync) synchronizes the Mailbox store, it doesn't mean it will sync BCM, or any other store.

This is usually a surprise to new users of ActiveSync, Outlook Connector, and other programs to synchronize Outlook with devices (PDAs, Smartphones) or the cloud. Most of these programs were designed to synchronize the Mailbox only. A proper contacts synchronizer for Outlook would ask you which MAPI stores and folders you want to synchronize, instead of only synchronizing the Contacts folder in the Mailbox store.