Section 113
SEC. 113. A master bound for a foreign port must make oath that he will not receive nor convey any letters or other packets which have not been regularly posted and received from the post-office at the port of departure, except letters or letter packets relating to the cargo and addressed to the owner or consignee of the vessel and letters or letter packets inclosed in properly stamped envelopes of sufficient denomination to cover the postage. The collector or other officer shall require from the master, as a condition of clearance, an oath or affirmation that he has not under his care, or within his control, and will not receive or convey any letters or letter packets in violation of this provision.