The Distribution-List object represents a group of Mail-Recipient objects. Any object that inherits from a Mail-Recipient object can be contained within a Distribution-List object. These include Public-Folder, Mailbox, and Remote-Address objects. A Distribution-List object can also contain other Distribution-List objects.
Because Distribution-List objects appear to MAPI as messaging user objects, use the MAPI IDistList interface to access a Distribution-List object.