Steps to manually recreate the sync relationship on mobile devices synchronizing with Microsoft Exchange Server. In some troubleshooting scenarios, users may need to rebuild and resynchronize their partnership manually.
In previous versions of Microsoft Exchange Server, if you moved your mailbox to an upgraded server (such as Exchange Server 2003 to Exchange Server 2007 RTM) recreating the partnership was required. However, if you move your mailbox to an Exchange Server 2007 with Service Pack 1, the new Sync State Upgrade feature is built into Move Mailbox and will allow you to continue synchronizing your device without resetting your partnership.
Exchange Server, Exchange Server 2003, Exchange Server 2007, Mobility, Synchronizing, Tips and Tricks, Guide