Contact Lists
04/30/2026
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
04/30/2026
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.

Data Files
04/30/2026
Z4 Info File

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

Data Files
04/30/2026
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.

 

Data Files
04/29/2026
Informed Visibility® Mail Tracking & Reporting (IV®-MTR) Development Tracker

This document provides a list of active IV-MTR work to be as well as items completed in FY25.

 

*Please note, Postal Pro is the only source for a current IV-MTR Development log as updates will be made on an ongoing basis.

Release Notes
04/29/2026
USPS APIs Release Notes

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

Release Notes
04/29/2026
Informed Visibility® Mail Tracking & Reporting (IV®-MTR) Release Notes

These release notes summarize new features and enhancements implemented in deployments to the IV-MTR application.

Fact Sheets
04/29/2026
Mailpiece Design Analyst (MDA) Customer Service Help Desk Brochure

An overview brochure for the MDA Customer Service Help Desk, including services, benefits, and contact information.

Release Notes
04/28/2026
User Guides
04/28/2026
Viewing MGI Credit Balances and Postage Statements

My Products Portal customers can view incentive credit balances and postage statements
associated with their account through the portal.