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.

USPS Ship Data Dictionary

Detailed information on the USPS Ship (Formerly Package Platform) data elements available through the Informed Visibility Mail Tracking & Reporting (IV-MTR) application. Please note that items in bold text were updated or added recently.

Mail Service Provider (MSP) - Full-Service Certified Mailers

A Mail Service Provider (MSP) offers a variety of solutions to prepare and present Full-Service presort mailings. For more information regarding Certified MSPs, please follow this link: https://postalpro.usps.com/full-service-cert/fact-sheet

Z4 Info File

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

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.

INFORMATIONAL - 2026 Labeling List and Mail Direction File (MDF) Timeline

2026 Small Business Symposium at NPF

Join us at the 2026 Small Business Symposium hosted at the National Postal Forum. Learn how small businesses leverage mail and shipping solutions to find success!

INFORMATIONAL -Don’t Miss the 2026 National Postal Forum

Pay Permit Fees and Auto-Fee Renewal Fact Sheet

Please note that the BCG user must be the BSA or BSA delegate for manage mailing activity and be the EPS administrator or payment manager to use this service.

Informed Visibility® Mail Tracking & Reporting (IV®-MTR) Operation Codes List

This spreadsheet provides a list of operation codes (opcodes), also known as Scan Event Codes, for the IV-MTR application.

Appendix B: ACS™ Frequently Asked Questions

This document provides frequently asked questions (FAQs) and answers about the Intelligent Mail® Barcode, Traditional ACS™, OneCode ACS™, Full Service ACS™, Single Source ACS™, and the Intelligent Mail® Package Barcode (IMpb).

INFORMATIONAL -PostalOne! System - INCIDENT 10567141 Error with Mail Entry Additional Postage Assessment Report

INFORMATIONAL - National Postal Forum 2026 Keynote Speaker – Jeremy Gutsche

USPS Ship Monthly Averages Tech Sheet

INFORMATIONAL - USPS Enhanced Addresses API – Coming July 2026

INFORMATIONAL - Informed Delivery Campaign Reporting Update April 2026

Addressing API License Agreement

INFORMATIONAL - 2026 National Postal Forum Leadership Insight Sessions

INFORMATIONAL - Package Tracking API Provisioning Cancelled