XADM: Benefits and Limitations of a Mixed-Mode Environment (280787)

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Benefits of Mixed-Mode Environments

When you run your Exchange Server organization in mixed mode, you ensure future interoperability between Exchange 2000 and earlier versions of Exchange Server. The benefits of operating a mixed-mode environment include:

• There is seamless interoperability between Exchange 2000 computers and Exchange 5.5 computers.
• All Exchange Server 5.5 directory service objects, such as servers and connectors, are replicated to Exchange 2000, and are displayed in the System Manager snap-in.
• There is seamless routing between Exchange 2000 and Exchange Server 5.5.
• Exchange 2000 can use existing Exchange Server 5.5 connectors and gateways to connect to foreign e-mail systems and route e-mail messages.
• Both Exchange Server 5.5 objects (users, custom recipients, and distribution lists) and Exchange 2000 objects (users, contacts, and groups) can be managed from Active Directory.
• You have the option to install Exchange Server 5.5 computers at a later time.
• Public folders that are replicated between Exchange 2000 and Exchange Server 5.5 can be securely accessed from clients on either system.

Limitations of Mixed-Mode Environments

NOTE: Because of the limitations of a mixed-mode environment, you should not operate in mixed mode if your organization uses Exchange 2000 computers, and if you are sure your network will not connect to earlier versions of Exchange Server in the future.

The limitations of operating a mixed-mode environment include:

• Exchange Server 5.x sites are mapped directly to administrative groups.
• Administrative groups are mapped directly to Exchange 5.x sites.
• You can only move mailboxes between servers that are in the same administrative group.
• Routing group membership must consist only of servers that are installed in the administrative group that is defined with the routing group.

NOTE: In an Exchange Server 5.x site, you manage the servers as a single group, and all the servers have full-mesh connectivity for sending messages to one another. However, when you operate your Exchange 2000 organization in mixed mode, and Exchange Server 5.x sites are mapped one-to-one with administrative groups, you can subdivide the routing structure for the Exchange 2000 computers in the collection by using routing groups. A server cannot belong to a routing group that is held under a different administrative group.