Contact Lists
11/20/2025
DPV® Licensees Cycle O: Certified Products Guide - (Expires July 31, 2028)
Contact Lists
11/20/2025
CASS™ Software Manufacturers Data File Cycle O: Certified Products Guide (D) - (Expires July 31, 2028)
Contact Lists
11/20/2025
CASS™ Software Manufacturers Cycle O - (Expires July 31, 2028)
Contact Lists
11/20/2025
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
11/20/2025
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.

Data Files
11/20/2025
Z4 Info File

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

Data Files
11/20/2025
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.

 

Release Notes
11/19/2025
Tracking API Access Control Changes Release Overview
Announcements
11/19/2025
DELIVERY - Southern Area – South Carolina District Sunset Post Office (29685) – Closed Indefinitely
User Guides
11/19/2025
Mailing and Shipping Solutions Center (MSSC) Topics

List of topics the MSSC can assist with. To reach the MSSC, email us at MSSC@usps.gov or call 1-877-672-0007 from 7:00AM – 7:00PM CT.