CASS Certification and Zip+4

CASS Certification is a process in which your data is processed through Postal software in order to standardize addresses. CASS Certification increases the address quality and improves deliverability of your mailpiece.

When processing a database through CASS Certification software, the standardization allows for correction of the street address, city, state, and zip code. In this process, the Zip+4 is added to the end of the zip code, which helps streamline sortation and delivery at the Post Office. CASS Certification will correct undeliverable addresses, therefore eliminating undeliverable mail. 

CASS Certification is required to be done on bulk mailing within 180 days of the mail date. By standardizing address, you are not only increasing the delivery time of your mailpiece, but you will also be saving money. ​