1-2 The DUNS/Mailer ID Number

Essential to procedures described in this publication is a unique nine-digit number used to identify a business. Throughout this publication, the nine-digit number is referred to as a DUNS® number — DUNS is an abbreviation for Data Universal Numbering System, which is administered by Dun & Bradstreet. Previously, Postal Service customers had to obtain a DUNS number in order to participate in the programs described in this publication. However, effective August 2007, the Postal Service replaced the DUNS number with a Mailer ID number — but this change does not impact any customer who had previously used a DUNS number, because the customer’s DUNS number still serves as the customer’s Mailer ID number. A new customer who applies for services will be assigned a Mailer ID number by Confirmation Services Support (see 1-3). Throughout this publication, the term “DUNS number” refers to the customer’s unique nine-digit number, whether it is actually a DUNS number or a Mailer ID number.

The customer’s nine-digit number makes it possible for the Postal Service to provide delivery information in bulk. This number is associated with a particular business to identify the mailer. It allows mail owners or their third-party designees to generate a unique tracking number that distinguishes their mailpieces from those of other mailers. Whether the mail owner or a designated third party is the actual mailer, the barcode represents that mailer’s identification number as part of the Package Identification Code (PIC). The PIC also appears as human-readable numbers below the barcode on the label.