Contact Lists
03/19/2026
CASS™ Software Manufacturers Data File Cycle O: Certified Products Guide (D) - (Expires July 31, 2028)
Contact Lists
03/19/2026
CASS™ Software Manufacturers Cycle O - (Expires July 31, 2028)
Contact Lists
03/19/2026
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.

Release Notes
03/19/2026
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.

Data Files
03/19/2026
Z4 Info File

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

Data Files
03/19/2026
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
03/18/2026
INFORMATIONAL: 2026 National Postal Forum - New NPF Vignettes Track
Announcements
03/18/2026
INFORMATIONAL - Kansas City Processing and Distribution Center New Package Sorting Equipment Installation
Announcements
03/18/2026
DELIVERY - International Service Suspension Notice March 20, 2026 - Lebanon
Technical Specifications
03/18/2026
USPS API MCAT - TechSheet

Coming soon..