Data type: PtypObject ([MS-OXCDATA] section 2.11.1)

The PidTagAddressBookUnauthorizedSenders property<35> ([MS-OXPROPS] section 2.574) indicates whether delivery restrictions exist for the specified recipient. A value other than NULL indicates that delivery restrictions exist for this recipient. The address book does not contain the lists of senders who are prohibited for this recipient; it only indicates whether such restrictions exist.