CASS Certification

(Coding Accuracy Support System)

A Bulk Mailing Requirement


For any mail that you wish to send bulk rate, it will need to be CASS Certified

This allows the post office to mail out our prepared mailing pieces more efficiently, due to correct addresses and a higher percentage of mailable pieces. It used to be that we could just sort via zip codes, but the post office was becoming very inefficient from mailing to bad addresses and the waste factor was too high. No one is allowed to send bulk mailings anymore without this certification.

We are a preferred vendor of the post office

We have the very expensive software that allows us to filter your database, certify, properly delete bad addresses and duplicates, and provide the proper certification to the post office that says your data and mailing pieces are good to be mailed. We can provide a copy of this paperwork to our customers upon request.


According to the United States Post Office:

The CASS system improves the accuracy of carrier route, five-digit ZIP®, ZIP + 4®, and delivery point codes that appear on mail pieces. 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 are 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 the following areas: (1) five-digit coding, (2) ZIP + 4/ delivery point (DP) coding, (3) carrier route coding, (4) DPV®, (5) DSF2®, (6) LACSLink® (7) eLOT® and (8), RDI™ products. CASS allows vendors/mailers the opportunity 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 diagnose internally written, commercially-available, address-matching software packages. The effectiveness of service bureaus' matching software can also be measured.

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