Contact Lists
05/08/2025
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
05/08/2025
Z4 Info File

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

Data Files
05/08/2025
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.

 

Technical Specifications
05/07/2025
Release Notes
05/07/2025
Tech Guides
05/06/2025
eVS to USPS Ship Migration Tech Sheet

The Postal Service is retiring the electronic verification system (eVS). eVS customers must migrate to USPS Ship or USPS APIs by February 2025. This includes customers using Premium Forwarding Services Commercial (PFSC) and Click N Ship BusinessPro (CNBPro). This document outlines the differences between the two platforms and steps to migrate from eVS to USPS Ship.

Fact Sheets
05/06/2025
eVS and USPS Ship Online Report and IV®-MTR Data Feed Comparison

eVS and USPS Ship Online Report and Informed Visibility® Mail Tracking & Reporting IV®-MTR Data Feed Comparison