Migrating from Exchange Server 5.5 to Exchange Server 2003

 

This topic provides instructions for migrating your organization from Microsoft® Exchange Server 5.5 to Exchange Server 2003. Furthermore, because it is recommended that you run your new Exchange Server 2003 organization in native mode, this topic discusses the advantages of native mode, and provides instructions for switching from mixed mode to native mode.

Specifically, this topic will:

• Provide you with the information necessary to migrate your Exchange 5.5 mailboxes and public folders to Exchange Server 2003.

• Show you how to use the Microsoft Active Directory® directory service tools.

• Provide you with the requirements necessary to install Exchange Server 2003.

• Show you how to run ForestPrep.

• Show you how to run DomainPrep.

• Show you how to run Exchange Setup.

• Provide you with information about how to move mailboxes and public folders.

• Provide you with information about how to switch your Exchange Server 2003 organization from mixed mode to native mode.

You Cannot Install Exchange Server 2003 on the Same Server as Exchange Server 5.5

It is important to note that there is no option for performing an in-place upgrade from Exchange Server 5.5 to Exchange Server 2003. Specifically, you cannot upgrade a server running Exchange Server 5.5 to Exchange Server 2003. To upgrade your organization from Exchange Server 5.5 to Exchange Server 2003, you must instead install Exchange Server 2003 on a separate computer and then use Active Directory Connector (ADC) to connect it to your existing Exchange Server 5.5 organization. This process is detailed later in this topic.

Permissions for Migrating from Exchange Server 5.5 to Exchange Server 2003

After ensuring that your organization meets the necessary prerequisites, the procedures referenced in this topic guide you through the deployment process.

Table 1 lists the required permissions or roles for the procedures referenced in this topic.

Table 1   Procedures referenced in this topic and corresponding permissions

Procedure	Required permissions or roles
Enable Microsoft Windows® 2000 Server or Microsoft Windows Server™ 2003 services	See Windows 2000 or Windows Server 2003 Help
Run ForestPrep on a domain controller (updates the Active Directory schema)	Enterprise Administrator Schema Administrator Domain Administrator Local Machine Administrator
Run DomainPrep	Domain Administrator Local Machine Administrator
Install Active Directory Connector (ADC)	Enterprise Administrator Schema Administrator Domain Administrator Local Machine Administrator
Install Exchange 2003 on the first server in a domain	Exchange Full Administrator role applied at the organization level Exchange 5.5 Administrator under the organization, site, and configuration nodes (if installing into an Exchange 5.5 site) Local Machine Administrator
Install Exchange 2003 on additional servers in the domain	Exchange Full Administrator role applied at the administrative group level Exchange 5.5 Site Administrator (if installing into an Exchange 5.5 site) Exchange 5.5 service account password Local Machine Administrator
Run Active Directory Account Cleanup Wizard	Enterprise Administrator

For more information about managing and delegating permissions and user and group authorities, see the Exchange Server 2003 Administration Guide.

Exchange 2003 Security Considerations

Before installing Exchange Server 2003 in your organization, it is important that you are familiar with your organization's security requirements. Familiarizing yourself with these requirements helps ensure that your Exchange 2003 deployment is as secure as possible. For more information about planning Exchange 2003 security, see the following guides:

• Planning an Exchange Server 2003 Messaging System

• Exchange Server 2003 Security Hardening Guide

Exchange Server Deployment Tools

The Exchange Server Deployment Tools are tools and documentation that help with your migration and validate that your organization is prepared for the Exchange Server 2003 installation. To ensure that all of the required tools and services are installed and running properly, it is recommended that you use the Exchange Server Deployment Tools to run Exchange Server 2003 Setup. For detailed steps, see How to Start the Exchange Server Deployment Tools.

After you start the tools and specify that you want to follow the process for Coexistence with Exchange 5.5, you are provided with a checklist detailing the installation steps. This checklist is separated into three phases:

Phase 1

1. Verify that your organization meets the specified requirements.

2. Run the DCDiag tool.

3. Run the NetDiag tool.

Phase 2

1. Run ForestPrep.

2. Run DomainPrep.

3. Run Active Directory Connector Setup.

4. Run Active Directory Connector tools.

Phase 3

• Run Exchange Setup.

With the exception of running the DCDiag and NetDiag tools, each of these installation steps is detailed later in this topic (it is recommended that you run the DCDiag and NetDiag tools on every server on which you plan to install Exchange Server 2003). Moreover, the remaining sections in this topic provide information about the concepts and considerations involved in migrating from Exchange Server 5.5 to Exchange Server 2003.

Active Directory and Exchange Server 5.5 Considerations

Before installing Exchange Server 2003, you should familiarize yourself with certain Active Directory and Exchange Server 5.5 directory considerations. Specifically, this section will provide you with information about migrating your Windows user accounts and synchronizing your Exchange Server 5.5 directory with Active Directory.

Exchange Directory Service and Windows NT User Accounts

In Microsoft Windows NT® Server 4.0 and Exchange Server 5.5, when you create a user and assign that user a mailbox, you associate a Windows NT user account with a mailbox object in the Exchange directory. A Windows security identifier (SID) is a unique number that makes this association. Every computer and user account on a network running Windows NT has an SID.

Active Directory User Objects and Directory Synchronization

Unlike earlier versions of Exchange and Windows NT, Active Directory contains a single object that has default user attributes and Exchange-specific attributes. When you populate Active Directory with user objects in an organization that includes an earlier version of Exchange, the user objects in Active Directory do not include Exchange-specific attributes. When you install Exchange Server 2003, Exchange extends user objects in Active Directory to include Exchange-specific attributes.

Exchange Server 5.5 has its own directory service, which, by default, cannot communicate with Active Directory and Exchange Server 2003. Therefore, Exchange Server 2003 Active Directory Connector (ADC) is used to allow communication and synchronization between the Exchange Server 5.5 directory and Active Directory.

ADC populates and synchronizes Active Directory with mailbox, custom recipient, distribution list, and public folder information from the Exchange Server 5.5 directory. Similarly, ADC also populates and synchronizes the Exchange Server 5.5 directory with user, contact, and group information from Active Directory. For more information about using ADC, see "Active Directory Connector" later in this topic.

Populating Active Directory

Before synchronization can occur, you must populate Active Directory with user information from your existing directory service. Active Directory is populated when your Windows NT 4.0 user account information and Exchange-specific object information from your Exchange Server 5.5 directory service reside in Active Directory.

Your deployment plan may require a combination of the methods described in the following section.

Populating User Information from Windows NT

To populate Active Directory with Windows NT user account information from an existing Windows NT 4.0 deployment, use one or both of the following methods:

• Upgrade existing Windows NT 4.0 user accounts to Active Directory user accounts.

• Use Active Directory Migration Tool to create cloned user accounts that preserve security information.

Upgrading Existing User Accounts

One method of populating Active Directory is to upgrade the Windows NT primary domain controller in the domain that contains your user accounts to a Windows 2000 or Windows Server 2003 domain controller. When you upgrade a Windows NT user account, you preserve all account information, including the SID.

Using Active Directory Migration Tool

Another method of populating Active Directory is to use Active Directory Migration Tool to clone the accounts in Active Directory.

A cloned account is an account in a Windows 2000 or Windows Server 2003 domain that has been copied from a Windows NT 4.0 source account to a new (cloned) user object in Active Directory. Although the new user object has a different SID than the source account, the SID of the source account is copied to the new user object's SIDHistory attribute. Populating the SIDHistory attribute with the source account SID allows the new user account to access all network resources available to the source account, providing that trusts exist between resource domains and the cloned account domain.

When you run Active Directory Migration Tool, you specify a source Windows NT account (or domain) and a target container in Active Directory in which Active Directory Migration Tool creates cloned accounts.

Active Directory Connector

After you populate Active Directory with Windows NT 4.0 user and group accounts, the next step in your migration is to connect your Exchange Server 5.5 directory to Active Directory. Specifically, you must use either Active Directory Connector or the user domain upgrade method to add Exchange Server 5.5 mailbox attributes to the Active Directory users and groups that you copied to Active Directory.

Synchronizing Active Directory with the Exchange Server 5.5 directory during the migration process is necessary because Exchange Server 2003 uses Active Directory as its directory service. Active Directory Connector (ADC) is a synchronization component that updates object changes between the Exchange Server 5.5 directory and Active Directory. ADC synchronizes current mailbox and distribution list information from the Exchange Server 5.5 directory to Active Directory user accounts and groups, thereby eliminating the need for re-entering this data in Active Directory. If ADC finds a recipient object in the Exchange directory that does not have a matching SID in Active Directory, ADC creates a user object in Active Directory and stores the existing SID in the msexchmasteraccountSID attribute of the new object. By default, ADC searches for the Windows NT user account SID before searching for a new object's SID history. However, ADC will not find a matching SID in Active Directory if ADC replicates before correctly upgrading your existing Windows NT 4.0 user accounts.

If your migrated users have problems logging on to their mailboxes after you use Active Directory Migration Tool and Active Directory Connector, you can use the Exchange Server 2003 Active Directory Account Cleanup Wizard to merge the duplicate objects for mailbox logon purposes. For detailed steps, see How to Run the Active Directory Account Cleanup Wizard.

Installing Active Directory Connector

To install the Exchange Server 2003 version of ADC, you must have at least one server in each Exchange site running Exchange Server 5.5 SP3. The account you use to install ADC must be a member of the Enterprise Administrator, Schema Administrator, and Domain Administrator groups. The account must also be a Local Machine Administrator on the local machine. For detailed steps, see How to Install Active Directory Connector.

Using Active Directory Connector Tools

ADC Tools (Figure 1) lead you through the process of confirming that your Exchange Server 5.5 directory and mailboxes are ready for migration. ADC Tools are a collection of wizards and utilities that help you set up and configure your connection agreements. The tools also ensure that replication between your Windows NT 4.0 organization and Windows 2000 or Windows Server 2003 is functioning properly.

ADC Tools are configured to check your organization's configuration and connection agreements and provide a recommendation based on your configuration. It is strongly recommended that you accept the recommendation in Active Directory Connector Tool.

Figure 1   The Active Directory Connector Services Tools page

Specifically, the ADC Tools lead you through the processes of scanning your directory, running Resource Mailbox Wizard, running Connection Agreement Wizard, and verifying synchronization. For detailed steps, see How to Run Active Directory Connector (ADC) Tools.

Resource Mailbox Wizard

The Resource Mailbox Wizard identifies Active Directory and Windows NT 4.0 accounts that match more than one Exchange Server 5.5 mailbox. In Windows NT 4.0 and Exchange Server 5.5, you could have a user account that corresponded to more than one mailbox. Using Active Directory and Exchange Server 2003, a user account can no longer have more than one mailbox. You can use the Resource Mailbox Wizard to match the appropriate primary mailbox to the Active Directory account and assign other mailboxes with the NTDSNoMatch value, which designates the mailboxes as resource mailboxes. You can either make these changes online using the Resource Mailbox Wizard or export to a comma-separated value (.csv) file that you can update and import into the Exchange Server 5.5 directory.

Connection Agreement Wizard

The Connection Agreement Wizard recommends public folder connection agreements and recipient connection agreements based on your Exchange Server 5.5 directory and Active Directory configuration. You can then review the recommended connection agreements, and select those that you want the wizard to create. There are three kinds of connection agreements:

• Recipient connection agreements

  Recipient connection agreements replicate recipient objects and the data they contain between the Exchange directory and Active Directory.

• Public folder connection agreements

  Public folder connection agreements replicate public folder directory objects between the Exchange Server 5.5 directory and Active Directory.

• Configuration connection agreements

  During your initial Exchange Server 2003 installation, Exchange Server 2003 Setup creates a configuration connection agreement between Active Directory and your Exchange Server 5.5 site. Configuration connection agreements replicate Exchange-specific configuration information between the Exchange Server 5.5 directory and Active Directory. These agreements allow Exchange Server 2003 to coexist with Exchange Server 5.5.

  Figure 2   The Active Directory Connector Services page

  

System-Wide Requirements for Exchange Server 2003

Before you migrate to Exchange Server 2003, ensure that your network and servers meet the following system-wide requirements:

• You have Windows 2000 Server Service Pack 3 (SP3) Active Directory or Windows Server 2003 Active Directory.

• Each Exchange Server 2003 server has access to a Windows global catalog server that is no more than one Active Directory site away.

• You have Domain Name System (DNS) and Windows Internet Name Service (WINS) configured correctly.

• You have established NetBIOS, RPC, and TCP/IP connectivity between your Exchange Server 5.5 organization and your Windows domain controllers.

• You backed up your Exchange Server 5.5 databases, and your servers running Windows 2000 or Windows Server 2003.

• You have at least one server in each Exchange site running Exchange Server 5.5 SP3 to allow synchronization between the Exchange Server 5.5 directory and Active Directory.

For more information about Windows 2000 Server, Windows Server 2003, Active Directory, and DNS, see the following resources:

• Windows 2000 Help

• Windows Server 2003 Help

• Best Practice Active Directory Design for Exchange 2000

• Planning an Exchange Server 2003 Messaging System

Running Exchange 2003 ForestPrep

Exchange 2003 ForestPrep extends the Active Directory schema to include Exchange-specific classes and attributes. ForestPrep also creates the container object for the Exchange organization in Active Directory. The schema extensions supplied with Exchange Server 2003 are a superset of those supplied with Exchange 2000 Server.

In the domain where the schema master resides, run ForestPrep once in the Active Directory forest. (By default, the schema master runs on the first Windows domain controller installed in a forest.) Exchange Setup verifies that you are running ForestPrep in the correct domain. If you are not in the correct domain, Setup informs you which domain contains the schema master. For information about how to determine which of your domain controllers is the schema master, see Windows 2000 or Windows Server 2003 Help.

The account you use to run ForestPrep must be a member of the Enterprise Administrator and the Schema Administrator groups. While you are running ForestPrep, you designate an account or group that has Exchange Full Administrator permissions to the organization object. This account or group has the authority to install and manage Exchange Server 2003 throughout the forest. This account or group also has the authority to delegate additional Exchange Full Administrator permissions after the first server is installed.

You can run Exchange Server 2003 ForestPrep from either the Exchange Server Deployment Tools or from the Exchange Server 2003 CD. For information about how to run Exchange ForestPrep from the Exchange Server Deployment Tools, see "Exchange Server Deployment Tools" earlier in this topic. For detailed steps about how to run Exchange ForestPrep, see How to Run Exchange Server 2003 ForestPrep.

Running Exchange Server 2003 DomainPrep

After you run ForestPrep and allow time for replication, you must run Exchange Server 2003 DomainPrep. DomainPrep creates the groups and permissions necessary for Exchange servers to read and modify user attributes. The Exchange Server 2003 version of DomainPrep performs the following actions in the domain:

• Creates Exchange Domain Servers and Exchange Enterprise Servers groups.

• Nests the global Exchange Domain Servers into the Exchange Enterprise Servers local group.

• Creates the Exchange System Objects container, which is used for mail-enabled public folders.

• Sets permissions for the Exchange Enterprise Servers group at the root of the domain, so that Recipient Update Service has the appropriate access to process recipient objects.

• Modifies the AdminSdHolder template where Windows sets permissions for members of the local Domain Administrator group.

• Adds the local Exchange Domain Servers group to the Pre-Windows 2000 Compatible Access group.

• Performs Setup pre-installation checks.

The account you use to run DomainPrep must be a member of the Domain Administrators group in the local domain and a local machine administrator. You must run DomainPrep in the following domains:

• The root domain.

• All domains that will contain Exchange Server 2003 servers.

• All domains that will contain Exchange Server 2003 mailbox-enabled objects (such as users and groups), even if no Exchange servers will be installed in these domains.

• All domains that contain global catalog servers that Exchange directory access components may potentially use.

• All domains that will contain Exchange Server 2003 users and groups that you will use to manage your Exchange Server 2003 organization.

You can run Exchange Server 2003 DomainPrep from either the Exchange Server Deployment Tools or from the Exchange Server 2003 CD. For information about how to run Exchange DomainPrep from the Exchange Server Deployment Tools, see "Exchange Server Deployment Tools" earlier in this topic. For detailed steps about how to run Exchange DomainPrep, see How to Run Exchange Server 2003 DomainPrep.

Server-Specific Requirements for Exchange Server 2003

Before you install Exchange Server 2003, ensure that your servers meet the requirements that are described in this section. If your servers do not meet all of the requirements, Exchange Setup will stop the installation.

Hardware Requirements

The following are the minimum hardware requirements for Exchange Server 2003 servers:

• Intel Pentium or compatible 133 megahertz (MHz) or faster processor

• 256 megabytes (MB) of RAM recommended minimum, 128 MB supported minimum

• 500 MB of available disk space on the drive on which you install Exchange

• 200 MB of available disk space on the system drive

• CD-ROM drive

• SVGA or higher-resolution monitor

For more information about hardware requirements for front-end and back-end servers, see the guide Exchange Server 2003 and Exchange 2000 Server Front-End and Back-End Server Topology Guide.

File Format Requirements

To install Exchange Server 2003, disk partitions must be formatted for NTFS file system and not for file allocation table (FAT). This requirement applies to the following partitions:

• System partition

• Partition that stores Exchange binaries

• Partitions containing transaction log files

• Partitions containing database files

• Partitions containing other Exchange files

Operating System Requirements

Exchange Server 2003 is supported on the following operating systems:

• Windows 2000 SP3 or later

  Note

  Windows 2000 SP3 or later is available for download at the following site: Windows 2000 Service Packs. Windows 2000 SP3 or later is also a prerequisite for running Exchange Server 2003 ADC.

• Windows Server 2003

Installing and Enabling Windows 2000 or Windows Server 2003 Services

Exchange Server 2003 Setup requires that the following components and services be installed and enabled on the server:

• .NET Framework

• ASP.NET

• Internet Information Services (IIS)

• World Wide Web Publishing Service

• Simple Mail Transfer Protocol (SMTP) service

• Network News Transfer Protocol (NNTP) service

If you are installing Exchange Server 2003 on a server running Windows 2000, Exchange Setup installs and enables the Microsoft .NET Framework and ASP.NET automatically. You must install the World Wide Web Publishing Service, SMTP service, and NNTP service before running Exchange Server 2003 Installation Wizard.

For detailed steps about how to install the IIS prerequisites for Exchange Server 2003 on the Windows 2000 platform, see How to Install IIS Prerequisites for Exchange Server 2003 on Windows 2000.

For detailed steps about how to install the IIS prerequisites for Exchange Server 2003 on the Windows Server 2003 platform, see How to Install IIS Prerequisites for Exchange Server 2003 on Windows Server 2003.

Running Exchange Server 2003 Setup

After planning and preparing your Exchange organization in accordance with the requirements and procedures listed in this topic, you are ready to run Exchange Server 2003 Setup. When running Setup, it is recommended that you join your existing Exchange Server 5.5 organization. By joining your Exchange Server 5.5 organization, you can move your mailboxes and public folders more easily.

For detailed steps, see How to Install Exchange Server 2003.

After Exchange Server 2003 Setup finishes, make sure that the SRS service is running. If the SRS service is not started, restart the SRS service.

For important information about post-deployment steps, see Post-Installation Steps for Exchange Server 2003. That topic includes information about how to verify that your Exchange installation was successful. It also includes information about the latest Exchange Server 2003 service packs and security patches.

Moving Exchange Server 5.5 Mailbox and Public Folder Contents

After you have populated Active Directory with Windows NT 4.0 objects, connected the Exchange Server 5.5 directory to Active Directory, and installed your first Exchange Server 2003 server into the Exchange Server 5.5 site, your next migration task is to move your Exchange Server 5.5 mailbox and public folder contents into the Exchange Server 2003 organization.

This section provides information about using Exchange Task Wizard to move your mailbox contents and using Microsoft Exchange Public Folder Migration Tool (PFMigrate) to move your public folder contents.

Using Exchange Task Wizard to Move Mailboxes

Exchange Task Wizard provides an improved method for moving mailboxes. You can now select as many mailboxes as you want, and then using the task scheduler, schedule a move to occur at a specified time. You can also use the task scheduler to cancel any unfinished moves at a specified time. For example, you can schedule a large move to start at midnight on Friday and terminate automatically at 6:00 A.M. on Monday, thereby ensuring that your server's resources are not being used during regular business hours. Using the wizard's improved multithreaded capabilities, you can move as many as four mailboxes simultaneously.

For detailed steps about how to move mailboxes using the Exchange Task Wizard, see How to Use Exchange Task Wizard to Move Mailboxes.

Using Microsoft Exchange Public Folder Migration Tool

The Microsoft Exchange Public Folder Migration Tool (PFMigrate) is a new tool that enables you to migrate both system folders and public folders to the new server. You can use PFMigrate to create system folder and public folder replicas on the new server and, after the folders have replicated, remove replicas from the source server. Unlike Exchange Server 5.5, you do not need to set a home server for a public folder in Exchange Server 2003. Any replica acts as the primary replica of the data it contains, and any public folder server can be removed from the replica list.

To determine how many system folders or public folders need to be replicated, use PFMigrate to generate a report before you actually run the tool. To determine whether the folders replicated successfully, you can generate the same report after you run the tool.

The PFMigrate tool is run from the Exchange Server Deployment Tools. For more information about how to start Exchange Server Deployment Tools, see "Exchange Server Deployment Tools" earlier in this topic.

For detailed steps, see How to Run the Public Folder Migration (PFMigrate) Tool.

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.

  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.

• 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.

• 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.

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.

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.

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 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.