Question: How to avoid the new Exchange Server 2003 users to be re-homed when you upgrade the forest to a Microsoft Windows Server 2003 native forest functional level? Answer: When you upgrade the forest to a Microsoft Windows Server 2003 native forest functional level, the Recipient Update Service may overwrite the value of the homeMDB attribute for new Microsoft Exchange Server 2003 users. This behavior may cause the mailboxes for the new Exchange Server 2003 users to be re-homed on the first mailbox store in the first storage group. We have to modify the purportedSearch attribute before you upgrade to a Windows Server 2003 native forest functional level. To do this, follow these steps: 1. Start Active Directory Service Interfaces (ADSI) Edit. (Note: Please ensure that you have installed Windows Server 2003 Support Tools. Using ADSI Edit to Edit Active Directory Attributes http://technet.microsoft.com/en-us/library/bb124152(EXCHG.65).aspx ) 2. Double-click the Configuration container, expand CN=Services, expand CN=Microsoft Exchange, and then expand CN=<ExchangeOrganizationName>. 3. Click CN=System Policies. 4. In the right pane, right-click CN=Mailbox Enable User, and then click Properties. 5. Scroll down to select the purportedSearch attribute, and then click Edit. 6. Clear the attribute, and then use the following filter to configure the attribute: (&(objectCategory=person)(objectClass=user)(mailnickname=*)(homeMdb=*)) 7. Click OK to save the change, and then close ADSI Edit. More information: Search filter change is required for Recipient Policy http://technet.microsoft.com/en-us/library/aa996257.aspx Address List and EAP filter upgrades with Exchange Server 2007 http://msexchangeteam.com/archive/2007/01/11/432158.aspx The Adsiedit.msc GUI tool is included when you install Windows Server 2003 Support Tools from the product CD or from the Microsoft Download Center (http://go.microsoft.com/fwlink/?LinkId=100114 ). For more information about how to install Windows Support Tools from the product CD, see Install Windows Support Tools (http://go.microsoft.com/fwlink/?LinkId=62270 ). Applies to: Microsoft Exchange Server 2003, Microsoft Exchange Server 2007