Microsoft KB Archive/822446

= Overview of the Differences Between Mixed Mode and Native Mode in Exchange Server 2003 =

Article ID: 822446

Article Last Modified on 11/9/2005

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APPLIES TO


 * Microsoft Exchange Server 2003 Enterprise Edition
 * Microsoft Exchange Server 2003 Standard Edition

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SUMMARY
An Exchange Server 2003 organization operates in one of two modes: mixed mode or native mode. This article describes the differences between mixed mode and native mode.

Important After an Exchange Server 2003 organization is changed to native mode, it cannot be reverted to mixed mode.



Exchange 2003 Servers in a Mixed Mode Exchange Organization
Mixed mode is the default operating mode of Exchange Server 2003. Mixed mode organizations have the following characteristics:
 * Different versions of Exchange Server can coexist in the same organization.
 * Functionality is limited to features that are shared by versions of Exchange Server that exist in the organization.
 * Rules that apply to earlier versions of Exchange Server also apply to later versions, even though those limitations may not exist in the later version.

To other Microsoft Exchange Server 4.x, Microsoft Exchange Server 5.0, and Microsoft Exchange Server 5.5 computers in the organization, the Exchange Server 2003 computer appears as just another server. The servers send out directory replication notifications in the standard manner, and the SRS database requests changes in the same way that earlier versions of Exchange Server request changes.

The following limitations apply to Exchange Server 2003 and Exchange 2000 Server when they run in a mixed mode Exchange organization:
 * Exchange Server 5.0 and Exchange Server 5.5 sites are mapped directly to administrative groups.
 * Administrative groups are mapped directly to Exchange Server 5.0 and Exchange Server 5.5 sites.
 * Routing group membership is made up of servers that are installed in the administrative groups only.

Exchange 2003 Servers in a Native Mode Exchange Organization
Native mode Exchange organizations have the following characteristics:
 * Routing groups are made up of servers from multiple administrative groups. Likewise, servers can be moved between routing groups that exist in different administrative groups.
 * Simple Mail Transfer Protocol (SMTP) is the default routing protocol.
 * Mailboxes can be moved across administrative groups.
 * Query-based distribution groups can be created.
 * If routing bridgehead pairs are upgraded to Exchange Server 2003 in a native mode organization, they will use 8BITMIME data transfers instead of converting down to 7-bit. This saves bandwidth over routing group connectors.
 * In native mode, the Exchange information store automatically ignores and removes zombie access control entry (ACE) entries (applicable if you previously had Exchange 5.5 installed in the organization).
 * The InetOrgPerson object class can be mailbox-enabled or mail-enabled.

For Exchange Server 2003 to operate in a native mode organization, it requires the following:
 * When you have a configuration with Windows 2000 domain controllers and global catalog servers on the local network, these servers must have Windows 2000 Server SP3-or-later installed if they will communicate with the Exchange server or with Active Directory Connector (ADC).
 * You can change an Exchange Server 2003 organization to native mode only after all the servers in the organization are upgraded to Exchange Server 2003 or to Exchange Server 2000 SP3. All earlier releases of Exchange Server must be upgraded or decommissioned, and no earlier releases can be added to the Exchange organization again.

Note Servers cannot be moved between administrative groups in either mixed mode or native mode.

For additional information about switching an Exchange organization to native mode, click the following article number to view the article in the Microsoft Knowledge Base:

281088 XADM: When to Change an Exchange Organization to Native Mode

How to Determine the Mode of an Exchange 2003 Organization
To determine the current mode of an Exchange 2003 organization, follow these steps.

Note Mixed mode is the default operating mode of an Exchange Server 2003.


 * 1) Start Exchange System Manager; click Start, point to Programs, point to Microsoft Exchange, and then click System Manager.
 * 2) Right-click the organization, and then click Properties.
 * 3) On the General tab, view the Operation Mode box to verify the current operating mode.

Additional query words: XADM mixed-mode native-mode

Keywords: KB822446

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