An officer of the United States appointed by the postmaster general to hold his office. during the, pleasure of the former. Before entering on the duties of his office, he is required to give bond with surety to be approved by the postmaster general. Every postmaster is required to keep an office in the place for which he may be appointed; and it is his duty to receive and forward by mail, without delay, all letters, papers, and packets as directed; to receive the mails and deliver, at all reasonable hours, all letters, papers and packets to the persons entitled thereto.