Promoting an Exchange Server 2003 Organization from Mixed Mode to Native Mode

This topic gives you information about promoting an Exchange Server 2003 Organization from Mixed Mode to Native Mode.

Switching from Mixed Mode to Native Mode

Exchange Server 2003 and Exchange 2000 Server both take advantage of Active Directory, and therefore coexist in what is called a native mode organization. However, Exchange Server version 5.5 (and earlier) does not rely on Active Directory. This difference means that, when servers running either Exchange 2003 or Exchange 2000 coexist with servers running Exchange 5.5 (or earlier), the organization must run in what is named mixed mode. Some newer features and functionality in Exchange are unavailable when running in mixed mode. For example, routing groups function differently in mixed and native modes.

By default, a new Exchange 2003 organization runs in mixed mode until it is promoted to native mode. You can only promote an Exchange organization to native mode if there are no servers running Exchange 5.5 (or earlier), and if no instances of Site Replication Service (SRS) are running. Make sure that you have correctly upgraded all servers and any connectors before you switch to native mode. After you switch an organization to native mode, it can never return to mixed mode. This means you cannot add an Exchange 5.5 server to a native mode topology. For detailed instructions, see How to Switch from Mixed Mode to Native Mode.