A bill to amend title 39, United States Code, to assure that the 9-digit ZIP Code remains voluntary, and for other purposes.

Requires that use of the nine-digit ZIP code remain voluntary. Allows the United States Postal Service to offer a voluntary rate incentive for use of a nine-digit ZIP code in efforts to hold down postal costs through automated processing of mail using such code.

Prohibits the Postal Service from: (1) publicly urging household mailers to use such codes; or (2) making any mass mailing to advise household addresses of their nine-digit codes. Directs the Postal Service to maintain systems to enable mailers to obtain information about such codes.

Requires the Postal Service to: (1) strive to maintain the same speed of mail service for mail bearing the five-digit ZIP code as obtained for mail bearing the nine-digit code; and (2) maintain public information to monitor any difference in service speed.