A Post Office Box may appear as a shipper or consignee address only in those limited cases where it is the only identifiable physical location where the cargo originated or will be delivered.  In certain foreign countries, Post Office Boxes may be the only address convention available.  However, Post Office Box mailing addresses must not be provided in lieu of a physical address when a more precise physical address may be identified.   In any case, the identification of a Post Office Box as an address in either the shipper or consignee address field may subject the cargo to further scrutiny by CBP Officers.