You can use Windows Management Instrumentation to mail-disable a MAPI public folder in a mixed-mode Exchange organization (824113)

CAUSE

This problem occurs because WMI incorrectly reads the IsMailEnabled property. In a mixed-mode Exchange environment, this property is typically blocked, and changes are not permitted.

In a mixed-mode Exchange environment, the user interface does not allow you to mail-disable MAPI public folders (the public folders under the MAPI folder tree). In WMI, there is a public folder provider with the class Exchange_PublicFolder. This class has a Boolean property named IsMailEnabled that tells you if a public folder is mail-enabled. This property is read/write, but if Exchange is in mixed mode, it is expected that you cannot mail-disable a MAPI public folder by using the property. However, with WMI, this property has not been blocked, and therefore you can mail-disable MAPI public folders in a mixed-mode Exchange environment by using the IsMailEnabled property in the Exchange_PublicFolder class.