XADM: Cannot Mail-Disable a Public Folder in Mixed Mode

When an Exchange 2000 Server organization is running in mixed mode, you may not be able to mail-disable a public folder that is located in the Messaging Application Programming Interface (MAPI) public folder tree.

To work around this problem and mail-disable a public folder that is located in the MAPI public folder tree, you need to switch your Exchange 2000 organization to native mode. Be aware of the implications of changing modes; the change to native mode cannot be reversed. For additional information about Exchange 2000 organization modes, click the article number below to view the article in the Microsoft Knowledge Base:

This behavior is by design.