Exchange Server Modes

An Exchange Server 2003 organization runs in one of two modes of operation: mixed mode or native mode. The following table defines each mode and identifies characteristics of each.

Mode Type	Description
Mixed	Mixed mode is the default Exchange mode that is designed for backwards compatibility with other Exchange servers. When operating in mixed mode: Overall Exchange functionality is limited to features shared by all servers in the organization. Exchange 2003 servers appear as just another server to earlier versions of Exchange. Used mixed mode if your organization includes servers running previous versions of Exchange.
Native	An organization in native mode contains only computers that are running Exchange 2000 Server or Exchange Server 2003 or later. To switch to native mode, the following conditions must exist: All Exchange servers must be upgraded to Exchange Server 2003. Domain controllers that communicate with Exchange servers must be running Windows 2000 Server SP3 or later. Note: After you change to native mode, you cannot change back to mixed mode. This means that no earlier releases can be added to the Exchange organization. It is important to understand the implications of the conversion before you convert. Use native mode to take advantage of the following features: Moving servers between routing groups in different administrative groups. Creating query-based distribution groups. Moving mailboxes between administrative groups. Mail-enabling or mailbox enabling the InetOrgPerson object.

To determine the mode of the Exchange organization, view the properties of the Organization object in Exchange System Manager. Edit the setting on the General tab to change the Exchange mode.