121 List Maintenance
Postal Addressing Standards provides guidance on the most efficient means to output an address to a mailpiece. It is necessary to begin with list maintenance, or list management, to ensure that the content of the address is accurate and complete. A variety of address information products and services is available to assist in list maintenance. The standards facilitate the use of these products by providing a uniform file format for data entry of address information, as well as for extraction of information for matching purposes.
It is recommended that delivery address information be stored in a minimum of 30 bytes or spaces in your computer system. The optimum recommendation is 64 bytes or spaces to be compatible with the Postal Service National ZIP+4 database.
The Postal Service defines a complete address as one that has all the address elements necessary to allow an exact match with the current Postal Service ZIP+4 and City State files to obtain the finest level of ZIP+4 and delivery point codes for the delivery address. A complete address may be required on mail at some automation rates. Refer to the Mailing Standards of the United States Postal Service, Domestic Mail Manual (DMM) for more detailed information.
A standardized address is one that is fully spelled out, abbreviated by using the Postal Service standard abbreviations shown in this publication or as shown in the current Postal Service ZIP+4 file.