What is CASS?
CASS stands for Coding Accuracy Support System and is a system designed by the USPS to give reduced postage costs to bulk mailers by improving address quality. The basic idea is that if the USPS knows that you’re giving them a “good” address, then they don’t have to waste time (and money) validating the address themselves. This savings can then be passed on to the mailer in bulk. What does CASS consider a “good” address? As far as CASS is concerned, a good address is one which has the correct Zip+4 code, Carrier Route, Delivery-point Barcode digits (which means it’s deliverable), and eLOT codes. How does the USPS know that a mailer is giving them a “good” address? Answer: if the address was supplied by a bulk mailer who uses a CASS Certified engine. To get CASS Certified, the USPS sends you a large list of addresses to validate. If your address validation engine is at least a certain percentage correct, it will be certified.
