How to Convert from Mixed Mode to Native Mode in Exchange
An organization that is running in mixed mode can accommodate all versions of Exchange Server. An organization that is running in native mode can contain only Exchange 2000 Server or later computers; new Exchange Server 5.5 (or earlier) computers cannot be introduced into the organization. By default, Exchange 2000 Server and Exchange Server 2003 are installed in mixed mode.
You can convert an Exchange organization to native mode after all of the servers are upgraded to Exchange 2000 or later, and earlier release restrictions no longer apply. You cannot switch to native mode until you either upgrade or decommission Exchange Server 5.5 (or earlier) computers.
The following are some of the features of Exchange native mode:
Routing groups can consist of servers from multiple administrative groups.
Ability to move servers between routing groups.
Simple Mail Transfer Protocol (SMTP) is the default routing protocol.
Before You Begin
Before you can convert an Exchange organization from mixed mode to native mode, all of the computers in the organization must be running Exchange 2000 or later.
After converting the Exchange organization to native mode, you cannot change back to mixed mode. This is a one-time conversion, and you must fully understand the results before you proceed.
To convert from mixed mode to native mode in Exchange
Open Exchange System Manager.
In the console tree, right-click the organization that you want to switch to native mode, and then click Properties.
In <Organization Name> Properties, under Change operation mode, click Change Mode.
In the warning dialog box, click Yes if you are sure that you want to permanently switch to native mode. Click Apply to accept your new Exchange mode.
For More Information
For more information about mixed mode and native mode for Exchange Server, see the following Microsoft Knowledge Base articles:
270143, "XADM: Mixed Mode vs. Native Mode"
327779, "How To Convert from Mixed Mode to Native Mode in Exchange"
272314, "XADM: Preparing a Mixed Mode Organization for Conversion to Native Mode"