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Upgrading and Coexisting with Exchange 2010
Applies to: Exchange Server 2010
Exchange 2010 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:
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Exchange 2010 is deployed in an existing Exchange organization.
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More than one Exchange version provides messaging services to the organization.
When a large organization gradually transitions a messaging system from Exchange Server 2003 or Exchange 2007 to Exchange 2010, 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 2010 and an overview of the configuration steps that you must perform to maintain coexistence.
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 2000 Server |
Not supported |
|
Exchange Server 2003 |
Supported |
|
Exchange 2007 |
Supported |
|
Mixed Exchange 2007 and Exchange Server 2003 organization |
Supported |
 Important: |
|---|
| After you deploy a new Exchange 2010 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 2010–only organization is not supported. |
Exchange 2010 requires that 64-bit hardware be supported in a production environment.
You can only deploy Exchange 2010 in an Exchange 2003 or Exchange 2007 organization that operates in native mode.
To use Exchange System Manager to change the Exchange organization to native mode on an Exchange 2003 server-
Start Exchange System Manager. Click Start, point to Programs, point to Microsoft Exchange, and then click System Manager.
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Right-click the organization and then click Properties.
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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.
