Before deploying your first Exchange Server 2007 server you must apply the Exchange Server 2007 schema extensions.  Though you can allow Exchange to do this automatically during setup there are some scenarios where you may wish to do it as a separate process, such as applying the extensions in advance of the first installation, or using a different account for the schema extension than for the Exchange installation so as to perform each task with the minimum required privileges.

If you wish to apply the Exchange Server 2007 schema extension on a 32-bit domain controller that is the Schema Master there are first some pre-requisites that must be installed.  Note: for Exchange Server 2007 compatibility the Schema Master must be at least Windows Server 2003 with Service Pack 1 or Windows Server 2003 R2.

• .NET 2.0 with Service Pack 1
• MMC 3.0 (if the Schema Master is not running Windows Server 2003 R2)
• PowerShell

You will also need the 32-bit version of Exchange Server 2007 RTM or Exchange Server 2007 SP1.

Extending the Active Directory Schema for Exchange Server 2007

To extend your AD schema for Exchange Server 2007 follow these steps:

1. Log on to the Schema Master with an account that has Schema Admins and Enterprise Admins permissions.

   How To Find Servers That Hold Flexible Single Master Operations Roles
   

2. Verify that Schema updates have been enabled.

   Schema Updates Require Write Access to Schema in Active Directory
   

3. Perform a System State backup of the Schema Master.
4. Disabled outbound replication on the Schema Master.

   repadmin /options servername +DISABLE_OUTBOUND_REPL

5. Extract the Exchange setup files to a temporary location, and open a command prompt in that folder.
6. Prepare the legacy Exchange permissions.

   C:\temp\Exchange\setup.com /PrepareLegacyExchangePermissions

7. Prepare the Schema.

   C:\temp\Exchange\setup.com /PrepareSchema

8. Prepare the Forest.

   C:\temp\Exchange\setup.com /PrepareAD

9. Prepare the Domain.  Each domain that will hold Exchange servers or Exchange recipients must be prepared.

   C:\temp\Exchange\setup.com /PrepareDomain

   To prepare all Domains in the Forest in one action use the following.

   C:\temp\Exchange\setup.com /PrepareAllDomains

10. If the commands have run without error and you are satisfied with the health of your Schema Master you can re-enable outbound replication.

    C:\temp\Exchange\repadmin /options servername -DISABLE_OUTBOUND_REPL

Your Active Directory is now ready for the first Exchange Server 2007 installation.