Here is a few things from eventid.net: As per Microsoft: "This event indicates that the Recipient Update Service could not find the Address List Root object (addressBookRoots attribute of the MicrosoftExchange object in Active Directory). This could be because the Recipient Update Service is configured to communicate with a domain controller/global catalog that is no longer available, has been demoted, or has invalid configuration information". See MSEX2K3DB for more details. MSEX2K3DB from MS TechNet Explanation This event indicates that the Recipient Update Service could not find the Address List Root object (addressBookRoots attribute of the MicrosoftExchange object in Active Directory). This could be because the Recipient Update Service is configured to communicate with a domain controller/global catalog that is no longer available, has been demoted, or has invalid configuration information. User Action Check the server permissions using ADSIEdit or LDAP support tools that are available on the Windows 2000 compact disc. Check to see if the server has access to CN=Microsoft Exchange, CN=Services, CN=Configuration, DC=..... Verify that the Recipient Update Service has been configured to use the correct domain controller/global catalog. The Recipient Update Service had an incorrect domain controller listed. We had removed a Win2k domain controller and the Recipient Update Service (Enterprise Configuration) and (Domain) had the old controller listed. The fix was to go into exchange system manager, Recipients, Recipient Update Services, properties on the Recipient Update Service (Enterprise Configuration) and change the domain controller to a valid domain controller. Then right click and rebuild. This has to be done for the local domain as well. Hope that helps, MePH