39 C.F.R. § 268.1
In order to conduct its business, the Postal Service has the need to collect various types of personally identifiable information about its customers, employees and other individuals. Information of this nature has been entrusted to the Postal Service, and employees handling it have a legal and ethical obligation to hold it in confidence and to actively protect it from uses other than those compatible with the purpose for which the information was collected. This obligation is legally imposed by the Privacy Act of 1974, which places specific requirements upon all Federal agencies, including the Postal Service, and their employees. In implementation of these requirements, the following rules of conduct apply:
[45 FR 44273, July 1, 1980, as amended at 60 FR 57346, Nov. 15, 1995; 68 FR 56560, Oct. 1, 2003]