The definition of an administrative group is different in a mixed Exchange 5.5/Exchange 2000 installation. In this scenario, administrative groups are equivalent to Exchange 5.5 sites, for compatibility reasons.
An Exchange 2000 installation runs in one of two modes of operation: mixed mode or native mode. By default, when a server is added to an Exchange 5.5 or Exchange 2000 implementation, the system is set to mixed mode. This ensures the future interoperability of the Exchange 2000 system with an Exchange 5.5 system.
Changing the system from mixed mode to native mode is done by editing the properties on the Organization item in System Manager.
Warning Once the system has been changed to native mode, you cannot change it back to mixed mode.
To support interoperation with an Exchange 5.5 system, a number of limitations are imposed on systems running in mixed mode:
If you have installed an Exchange 2000 server in an Exchange 5.5 site, the following apply: