Contact Lists
10/16/2025
CASS™/MASS™ Certified Products Guide - All Sections Data Files Cycle O - (Expires July 31, 2028)

This document contains the certified vendors list for CASS™ and MASS™ products for Cycle O.

Data Files
10/16/2025
Z4 Info File

A downloadable ZIP file containing information related to the Z4 Info File

Data Files
10/16/2025
Early Warning System (EWS002C0.ZIP)

This file is the EWS production file and is updated weekly. This file contains the Early Warning System data file for the CASS™ and MASS™ certification process.

 

Announcements
10/15/2025
INFORMATIONAL - Atlantic AIM Meeting October 20, 2025
Release Notes
10/15/2025
USPS APIs Release Notes

For the latest updates, please review the USPS APIs Release Notes.

Contact Lists
10/15/2025
Business Acceptance Solutions & Major Mailer Support Directory

This document provides a contact list for Business Acceptance Solutions (formerly Business Mailer Support) & Major Mailer Support

 

Release Notes
10/14/2025
October 19 2025 Release Notes
Release Notes
10/14/2025
October 26 2025 Release Notes
Publications
10/14/2025
Destination Entry Service Standard Directory
Publications
10/14/2025
Combined Service Standard Directory-PRI