201 Switching from Mixed Mode to Native Mode Because Exchange Server 2003 is structured to take advantage of Active Directory functionality, there are some limitations when Exchange Server 2003 coexists in the same organization with Exchange Server 5.5. When Exchange Server 2003 servers coexist with Exchange Server 5.5, your organization must run in mixed mode. Running in mixed mode limits the functionality of Exchange Server 2003. Therefore, after migrating from Exchange Server 5.5 to Exchange Server 2003, it is recommended that you switch from mixed mode to native mode. This section discusses the advantages of a native-mode Exchange organization and provides the steps to switch from mixed mode to native mode. You are ready to change your Exchange Server 2003 organization to native mode if: Your organization will never require interoperability between your Exchange Server 2003 servers and Exchange Server 5.5 servers in the same organization. Your Exchange Server 5.5 servers exist in an organization that is separate from your Exchange Server 2003 servers. 202 Note: After you switch your Exchange Server 2003 organization from mixed mode to native mode, you cannot switch the organization back to mixed mode. Make sure that your Exchange Server 2003 organization will not have to interoperate with Exchange Server 5.5 in the future before you switch from mixed mode to native mode. First, you should determine in which mode your Exchange organization is currently running. For detailed steps, see How to Determine if You Are Running Exchange in Mixed or Native Mode. Exchange Server 2003 Considerations for Mixed and Native Mode As mentioned earlier, after you migrate from Exchange Server 5.5 to Exchange Server 2003, by default, your organization runs in mixed mode. Running Exchange Server 2003 in mixed mode has the following disadvantages: Exchange Server 5.5 sites are mapped directly to administrative groups. Administrative groups are mapped directly to Exchange Server 5.5 sites. 203 Routing group membership consists only of servers that are installed in the administrative groups. You cannot move Exchange Server 2003 servers between routing groups. Because many Exchange Server 2003 features are available only when you run your Exchange Server 2003 organization in native mode, it is recommended that you switch from mixed mode to native mode. Running Exchange Server 2003 in native mode has the following advantages: You can create query-based distribution groups. A query-based distribution group provides the same functionality as a standard distribution group. However, instead of specifying static user memberships, with a query-based distribution group you can use an LDAP query to build membership in the distribution group dynamically. For more information about query-based distribution groups, see "Managing Recipients and Recipient Policies" in the Exchange Server 2003 Administration Guide. Your routing bridgehead server pairs use 8BITMIME data transfers instead of converting down to 7-bit. This equates to a considerable bandwidth saving over routing group connectors. 204 The Exchange store in Exchange Server 2003 ignores and removes zombie access control entries (ACEs) from the previous Exchange Server 5.5 servers in your organization automatically. These zombie access control entries are security identifiers from previous Exchange Server 5.5 servers that have been removed from your organization. Routing groups can consist of servers from multiple administrative groups. You can move Exchange Server 2003 servers between routing groups. You can move mailboxes between administrative groups. Simple Mail Transfer Protocol (SMTP) is the default routing protocol. Removing Exchange 5.5 Servers Before you can switch from mixed mode to native mode, you must remove all Exchange Server 5.5 servers in your organization. This section guides you through the process of removing the Exchange Server 5.5 servers from your organization. 205 Removing an Exchange 5.5 Server Before you remove an Exchange Server 5.5 server from your site, verify that there are no mail connectors on the server. If there are, open a connector on another server in the site, and then verify mail flow. Next, remove the connectors on the server to be deleted. Retest message flow. For more information about removing your Exchange Server 5.5 connectors, see the Exchange Server 5.5 Help. For detailed steps about how to remove Exchange Server 5.5 servers, see How to Remove Exchange 5.5 Servers from Your Exchange 2003 Organization. Note: Ensure that the account to which you are logged on has Exchange Full Administrator permissions, as well as Exchange Server 5.5 service account administrator permissions for the site. Important: If this is the first server in the site to be removed, see Microsoft Knowledge Base article 152959, "XADM: How to Remove the First Exchange Server in a Site" (http://go.microsoft.com/fwlink/?linkid=3052&kbid=152959). 206 Removing the Last Exchange Server 5.5 Server Before you can switch from mixed mode to native mode, you must remove all Exchange Server 5.5 servers in your organization. This section guides you through the process of removing the last Exchange Server 5.5 server from your organization. For detailed steps, see How to Remove the Last Exchange 5.5 Server from Your Exchange 2003 Organization. Removing Site Replication Service Site Replication Service (SRS) is a component that exchanges configuration information between Active Directory and the directory in Exchange Server 5.5. In Exchange Server 5.5, SRS is necessary because Exchange Server 5.5 configuration information can only be exchanged between Exchange Server 5.5 servers and Exchange Server 5.5 directories—not with Active Directory. SRS mimics an Exchange Server 5.5 directory so that other Exchange Server 5.5 servers can replicate information to it. Using the configuration connection agreement created by Exchange Setup, Active Directory Connector replicates the configuration information in SRS into Active Directory. 207 SRS runs only in a mixed-mode Exchange administrative group. SRS also performs additional functions, such as detecting and reacting to directory replication topology changes. You cannot switch from mixed mode to native mode until you have removed all instances of SRS. SRS is enabled automatically in two situations: On the first Exchange Server 2003 server you install in an Exchange Server 5.5 organization. When you upgrade to Exchange 2000 Server from an Exchange Server 5.5 server that is the directory replication bridgehead server for an organization. For detailed steps on how to remove the Site Replication Service, see How to Remove Exchange SRS. After you complete these steps, you can convert the Exchange organization to native mode. Switching to Native Mode After you switch your Exchange Server 2003 organization from mixed mode to native mode, you cannot switch the organization back to mixed mode. Before you switch from mixed mode to native mode, ensure that 208 your Exchange Server 2003 organization will not have to interoperate with Exchange Server 5.5 in the future. For detailed steps about how to switch from mixed mode to native mode, see How to Convert from Mixed Mode to Native Mode in Exchange. To take full advantage of Exchange native mode, you must restart the Microsoft Exchange Information Store service on all of the Exchange servers in your organization. You do not need to restart all of the Microsoft Exchange Information Store services simultaneously, but you must restart the service on each server for the server to take advantage of all Exchange native mode features. Restart the service on your servers after the change to native mode has been replicated to your local Windows domain controller. For detailed steps on how to restart the information store service, see How to Restart the Microsoft Exchange Information Store Service. Uninstalling Exchange 2003 After ensuring that your organization meets certain prerequisites, you can run Exchange Setup to uninstall Exchange Server 2003. For detailed steps, see How to Uninstall Exchange Server 2003. 209 How to Run the Active Directory Account Cleanup Wizard If users who have been migrated from the Exchange 5.5 directory service have problems logging on to their mailboxes after you use the Active Directory Migration Tool and Active Directory Connector (ADC), you can use the Exchange 2003 Active Directory Account Cleanup Wizard to merge the duplicate objects for mailbox logon purposes. Before You Begin The account you use to install ADC must be a member of the Enterprise Administrator group. Procedure To run Active Directory Account Cleanup Wizard Click Start, point to All Programs, point to Microsoft Exchange, point to Deployment, and then click Active Directory Account Cleanup Wizard. Follow the instructions in the wizard to merge your duplicate user objects. Note: 210 While your Exchange 2003 organization coexists with Exchange 5.5, you must use ADC to maintain directory synchronization. For More Information For more information about using the Active Directory Account Cleanup Wizard to search for and remove duplicate accounts, see "Merge Duplicate Accounts in Active Directory" in the Exchange Server 2003 online Help. For more information about the Active Directory Account Cleanup Wizard, see the Microsoft Knowledge Base article 270652, "Possible Uses of the Active Directory Account Cleanup Wizard." How to Install Active Directory Connector Active Directory Connector (ADC) is used to connect your Exchange 5.5 directory to Active Directory. Before You Begin To install the Exchange 2003 version of ADC, you must have at least one server in each Exchange site running Exchange 5.5 SP3. . your Exchange Server 2003 servers and Exchange Server 5.5 servers in the same organization. Your Exchange Server 5.5 servers exist in an organization that is separate from your Exchange Server. Exchange Server 5.5. In Exchange Server 5.5, SRS is necessary because Exchange Server 5.5 configuration information can only be exchanged between Exchange Server 5.5 servers and Exchange Server. situations: On the first Exchange Server 2003 server you install in an Exchange Server 5.5 organization. When you upgrade to Exchange 2000 Server from an Exchange Server 5.5 server that is the