Client Access servers that are deployed in environments that have existing Exchange 2003 back-end servers enabled for RPC over HTTP will automatically use these back-end servers to access Outlook Anywhere. If you are supporting mailboxes that are running on Exchange 2003 with SP1 or a later version, you must follow these steps in order:

1. Install a valid Secure Sockets Layer (SSL) certificate from a certification authority (CA) that is trusted by the operating system of the client computer.
   
2. Install the Windows RPC over HTTP Proxy component.
   
3. Run the Enable Outlook Anywhere Wizard on at least one Client Access server in your Exchange deployment.
   
4. If you have not already enabled an Exchange 2003 server for RPC over HTTP access, use the Exchange System Manager RPC over HTTP user interface in Exchange 2003 to enable it.
   

After you enable Outlook Anywhere on an Exchange 2007 Client Access server in your organization, you can continue to add Exchange 2003 SP1 back-end servers or Exchange 2007 servers that have the Mailbox server role installed. The Client Access server will automatically manage access to these servers. However, if you add Exchange 2003 back-end servers that do not have Exchange 2003 SP1 or a later version, you must follow the instructions for enabling RPC over HTTP for Exchange 2003 without SP1. For more information, see Deployment Scenarios for RPC over HTTP.

If your Client Access servers are deployed in environments that include Exchange 2003 back-end servers that have not been upgraded to SP1 or a later version, you must manually configure your registry on the following servers to manage Outlook Anywhere:

• Client Access servers that are providing Outlook Anywhere access
  
• Exchange 2003 back-end servers
  
• Domain controllers
  

We recommend that you upgrade your Exchange 2003 servers to SP1 or a later version. If you must use Exchange 2003 servers that do not have SP1, you must follow these steps in order:

1. On the Client Access server, disable the RpcHttpConfigurator by editing the registry.
   
2. Follow the steps to deploy RPC over HTTP for Exchange 2003 servers. For more information, see Deployment Scenarios for RPC over HTTP.
   

To perform this procedure, the account you use must be delegated the Exchange Server Administrator role and membership in the local Administrators group for the target server.

For more information about permissions, delegating roles, and the rights that are required to administer Exchange 2007, see Permission Considerations.

Note:
Incorrectly editing the registry can cause serious problems that may require you to reinstall your operating system. Problems resulting from editing the registry incorrectly may not be able to be resolved. Before editing the registry, back up any valuable data.

For more information about Outlook Anywhere, see the following topics:

• Overview of Outlook Anywhere
  
• Managing Outlook Anywhere