[Code of Federal Regulations] [Title 39, Volume 1] [Revised as of July 1, 2003] From the U.S. Government Printing Office via GPO Access [CITE: 39CFR310.4] [Page 159] TITLE 39--POSTAL SERVICE CHAPTER I--UNITED STATES POSTAL SERVICE PART 310--ENFORCEMENT OF THE PRIVATE EXPRESS STATUTES--Table of Contents Sec. 310.4 Responsibility of carriers. Private carriers are cautioned to make sure that their carriage of matter is lawful within the definition, exceptions, suspension, and conditions contained in this part and in part 320 of this chapter. They should take reasonable measures to inform their customers of the contents of these regulations so that only proper matter is tendered to them for carriage. Carriers should desist from carrying any matter when the form of shipment, identity of sender or recipient, or any other information reasonably accessible to them indicates that matter tendered to them for carriage is not proper under these regulations.