The USPS Postal Numeric Encoding Technique (POSTNET) symbology was developed by the United States Postal Service (USPS) to help sort business reply and courtesy reply mail and was also used for regular bulk mailings. It was typically used in conjunction with the USPS Postal Alpha Numeric Encoding Technique (USPS PLANET) symbology.

In 2009, POSTNET was superseded by the USPS Intelligent Mail barcode (IMb), and PLANET was superseded by IMb in 2013.

The symbol can represent a five-digit ZIP Code, a nine-digit ZIP+4 Code, or an 11-digit delivery point barcode (DPBC). The USPS developed DPBC to uniquely identify each of 115 million delivery points in the United States. Its use greatly reduced the time that it took carriers to sort letter mail prior to delivery.

POSTNET is defined in the USPS Designing Letter and Reply Mail document.

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