Specifies the type of identifier for a StorageItem object.
Version Added: Outlook 2007
Identifies a StorageItem by EntryID.
Identifies a StorageItem by message class.
Identifies a StorageItem by Subject.
The message class of a StorageItem Object (Outlook) is not exposed as an explicit built-in property. You can access the message class property through the PropertyAccessor Object (Outlook) that is provided by StorageItem.PropertyAccessor Property (Outlook).