CASS™ Software Manufacturers Cycle O - (Expires July 31, 2028)

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.

Z4 Info File

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

Publication 401: Guide to the Manifest Mailing System

This publication provides information on the Manifest Mailing System, which automates the documentation of postage and fees for all pieces in a mailing paid via permit imprint indicia.

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.

Catalog Insights Promotion Webinar - Slides

See the slideshow below from the Catalog Insights Promotion webinar. Note that minor updates have been made to the slides, including updating language surrounding Bound Printed Matter and an additional slide on how to qualify for the Promotion. 

Post Office/ZIP Code Entries for Postal Bulletin 7/10/2025

This spreadsheet provides details on the Post Office/ZIP Code entry changes for Postal Bulletin issue 7/10/2025.

DELIVERY: International Service Resumption Notice - Effective July 4, 2025

Undeliverable-as-Addressed (UAA) Statistics by Mailing Industry Quarterly Report (Q3 FY25)

ACS Nixie stats by industry for FY25 Q3.

Address Matching System API (AMS API) Licensing Fees

This document outlines the AMS API prorated fee structure. License fees are prorated for the initial license year with a license year beginning October 1 and ending September 30.