CASS is offered to all mailers, service bureaus and software vendors who want to evaluate their address-matching software and improve the quality of their ZIP+4, CRIS, and five-digit coding accuracy. This process is graded by the United States Postal Service®, National Customer Support Center (NCSC), and the results returned to mailers in order to provide useful diagnostics for correcting deficiencies.

CASS enables the Postal Service™ to evaluate the accuracy of address-matching software programs in three areas: (1) ZIP+4 delivery point coding, (2) carrier route coding, and (3) five-digit coding. CASS allows vendors/mailers to test their address-matching software packages and, after achieving a certain percentage of compliance, to be certified by the Postal Service. CASS does not measure the accuracy of ZIP+4 delivery point, five-digit ZIP®, or carrier route codes in a mailer's existing files. CASS enables mailers to measure and examine internally written, commercially-available, address-matching software packages. The effectiveness of service bureaus' matching software also can be measured.