Applies to: Exchange Server 2007 SP3, Exchange Server 2007 SP2, Exchange Server 2007 SP1, Exchange Server 2007
Topic Last Modified: 2007-08-13

Microsoft Exchange Server 2007 can be deployed in an Active Directory directory service forest that has an existing messaging system. You have a coexistence scenario if the following conditions are true:

When a large organization gradually transitions a messaging system from Exchange 2000 Server or Exchange Server 2003 to Exchange 2007, the organization will probably have to maintain more than one version of Exchange during that time. This topic provides an overview of the coexistence scenarios that are supported for Exchange 2007 and an overview of the configuration steps that you must perform to maintain coexistence. For information about how to complete the transition from Exchange 2003 to Exchange 2007, see Upgrading to Exchange 2007.

Important:
Exchange 2007 does not support coexistence with Exchange Server version 5.5. Your Exchange organization must be operating in native mode to support coexistence with Exchange 2007.

Supported Coexistence Scenarios

Table 1 lists the supported coexistence scenarios with earlier versions of Exchange.

Table 1   Coexistence scenarios supported for earlier versions of Exchange Server

Exchange version Exchange organization coexistence

Exchange Server 5.5 

Not supported

Exchange 2000 Server 

Supported

Exchange Server 2003 

Supported

Mixed Exchange 2000 Server and Exchange Server 2003 organization

Supported
Note:
You can use the same procedures for Exchange 2007 coexistence with Exchange 2003 and Exchange 2007 coexistence with Exchange 2000. All procedures and documentation that refer to Exchange 2003 only also apply to Exchange 2000.
Important:
After you deploy a new Exchange 2007 organization, you can't add servers that are running earlier versions of Exchange to the organization. The addition of earlier versions of Exchange to an Exchange 2007–only organization is not supported.

Exchange 2007 requires that 64-bit hardware be supported in a production environment. Exchange 2007 cannot share hardware with Exchange 2003. However, if Exchange 2003 is currently installed on a server that uses 64-bit hardware, you can install Exchange 2007 on that server after Exchange 2003 is removed.

Deploying Exchange 2007 Server Roles to Coexist with Exchange 2003 and Exchange 2000

You can only deploy Exchange 2007 in an Exchange 2003 organization that operates in native mode. When an Exchange 2003 organization operates in native mode, the following conditions are true:

  • No servers that are running Exchange Server version 5.5 exist in the organization.

  • The Site Replication Service has been decommissioned.

  • Any Exchange Active Directory connectors have been decommissioned.

After these items have been removed, you must manually convert the Exchange organization to native mode.

To use Exchange System Manager to change the Exchange organization to native mode on an Exchange 2003 server or Exchange 2000 server

  1. Start Exchange System Manager. Click Start, point to Programs, point to Microsoft Exchange, and then click System Manager.

  2. Right-click the organization and then click Properties.

  3. Click the General tab, and then, under Change Operations Mode, click Change Mode. Click Yes if you are sure that you want to permanently switch the organization's mode to native mode.

All Exchange 2007 server roles are supported for coexistence with a native mode Exchange organization. When you deploy the first server roles for coexistence, follow the procedures in How to Install Exchange 2007 in an Existing Exchange Server 2003 Organization.

Table 2 lists the organizational Exchange 2007 server roles and the supported configuration for each role when Exchange 2007 coexists with Exchange Server 2003 and Exchange 2000 Server.

Table 2   Server roles and support

Exchange 2007 server role Supported configuration

Client Access server role
  • No other Exchange 2007 roles are required.

  • You must deploy a Client Access server role in each Active Directory site that contains the Mailbox server role.

  • Clients will see the Microsoft Office Outlook Web Access version that is on their mailbox store.

    Note:
       Users with mailboxes on an Exchange 2003 server who try to use Exchange ActiveSync through an Exchange 2007 Client Access server receive an error and cannot synchronize unless Integrated Windows Authentication is enabled on the Microsoft-Server-ActiveSync virtual directory on the Exchange 2003 server. This allows the Exchange 2007 Client Access server and the Exchange 2003 back-end server to communicate by using Kerberos authentication.

Hub Transport server role
  • No other Exchange 2007 server roles are required.

  • Routing group connectors must exist between the Exchange Routing Group (DWBGZMFD01QNBJR) and each Exchange Server 2003 routing group that communicates directly with Exchange 2007. The first routing group connectors are created during installation. We recommend that you use the Set-RoutingGroupConnector cmdlet to add source servers and target servers to these connectors for redundancy purposes.

  • You must suppress minor link state updates on every Exchange 2003 computer before you create additional routing group connectors that specify Exchange 2007 Hub Transport servers as source or target servers.

Unified Messaging server role
  • You must deploy an Exchange 2007 Hub Transport server in the same Active Directory site as the Unified Messaging server role.

  • Exchange Server 2003 computers cannot interoperate with the Unified Messaging server role. Exchange 2003 mailboxes cannot be Unified Messaging–enabled.

Mailbox server role
  • You must deploy the Exchange 2007 Hub Transport server role in the same Active Directory site as the Mailbox server role.
Note:
The Edge Transport server role is deployed outside the Exchange organization in the perimeter network. You can deploy an Edge Transport server as a Simple Mail Transfer Protocol (SMTP) relay and smart host server for your existing Exchange messaging infrastructure. However, a limited set of the Edge Transport server role features will be available. For more information about how to deploy the Exchange 2007 Edge Transport server role to support an existing Exchange organization, see How to Deploy an Edge Transport Server in an Existing Exchange Server 2003 Organization.

Managing a Mixed Exchange 2003, Exchange 2000, and Exchange 2007 Organization

In Exchange System Manager for Exchange 2000 and Exchange 2003, all Exchange 2007 servers are displayed as members of a single administrative group that is called Exchange Administrative Group (FYDIBOHF23SPDLT). All Exchange 2007 servers are also displayed as members of a single routing group that is called the Exchange Routing Group (DWBGZMFD01QNBJR). These objects are created for coexistence with Exchange 2000 Server and Exchange Server 2003 and should not be modified by using Exchange System Manager.

Caution:
Do not move Exchange 2007 servers out of Exchange Administrative Group (FYDIBOHF23SPDLT) and do not rename Exchange Administrative Group (FYDIBOHF23SPDLT) by using a low-level directory editor. Exchange 2007 must use this administrative group for configuration data storage. We do not support moving Exchange 2007 servers out of Exchange Administrative Group (FYDIBOHF23SPDLT) or renaming of Exchange Administrative Group (FYDIBOHF23SPDLT).
Caution:
Do not move Exchange 2007 servers out of Exchange Routing Group (DWBGZMFD01QNBJR) and do not rename Exchange Routing Group (DWBGZMFD01QNBJR) by using a low-level directory editor. Exchange 2007 must use this routing group for communication with earlier versions of Exchange. We do not support moving Exchange 2007 servers out of Exchange Routing Group (DWBGZMFD01QNBJR) or renaming of Exchange Routing Group (DWBGZMFD01QNBJR).
Important:
Do not include Exchange 2007 servers and Exchange 2003 or Exchange 2000 servers in the same routing group. This is not supported.

You must use the administrative tools that are specific to the Exchange server version that you are managing.

  • You manage Exchange 2007 server roles and mailbox recipients by using the Exchange Management Console or the Exchange Management Shell in Exchange 2007.

  • You manage Exchange 2000 and Exchange 2003 servers by using Exchange System Manager.

  • If you are using any features from Exchange 2000 that are not supported in Exchange 2003 or Exchange 2007, you must use Exchange 2000 System Manager to manage those features.

  • You can manage Exchange 2000 and Exchange 2003 recipients by using a management computer on which the administrative tools for both Active Directory and the Exchange 2003 are installed.

Mailboxes that are located on Exchange 2000 and Exchange 2003 servers are also displayed in the Exchange Management Console in Exchange 2007.

  • You can manage the Exchange 2000 and Exchange 2003 mailbox properties by using the Exchange Management Console in Exchange 2007.

  • To move mailbox recipients from Exchange 2000 and Exchange 2003 to Exchange 2007, you must use the Move-Mailbox cmdlet in the Exchange Management Shell.

For More Information