The CASS™ certification process is designed in cooperation with the mailing industry to improve the accuracy of postal codes, i.e., Five-Digit ZIP Code®, ZIP + 4®, delivery point (DPCs), and carrier route codes that appear on mailpieces.
The changes in CASS Cycle O are aimed at improving address quality, reducing undeliverable mail, and simplifying the system for mailers, the USPS, and recipients.