Contact Lists
11/05/2026
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
11/05/2026
Z4 Info File

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

Data Files
11/05/2026
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
11/04/2026
PROCESSING AND DISTRIBUTION - Update - Central Processing Region - Louisville, KY (PDC) Delays
Announcements
11/04/2026
DELIVERY - Westpac Area – Arizona – New Mexico District Blue Post Office – Temporarily Closed
Announcements
11/04/2026
DELIVERY - International Resumption of Mail Service - Effective November 6, 2026
User Guides
11/04/2026
Online Postage Due Permit Creation