The CreatorSearchKey property returns an identity stamp that uniquely identifies an item’s creator.
All Item objects
String
Read/write
The CreatorSearchKey property is set on an item only if another user creates the item; it is not available to an item created by the owner. The value is determined by the underlying mail transport system. Applications should use this property to verify that a user created a particular item. The format of the data in the property is not interpretable by most applications and should be treated like a handle.
CreatorEntryId
CreatorName
OwnerSearchKey