Contact Lists
10/15/2026
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.

Contact Lists
10/15/2026
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

 

Data Files
10/15/2026
Z4 Info File

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

Data Files
10/15/2026
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.

 

User Guides
10/14/2026
eDoc Submitter Credit Enrollment GuIde

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Presentations
10/14/2026
2027 Promotions Webinar Recording

NOTE: THE WEBINAR BEGINS AT THE 18:40 MARK

 

Recording of the 2027 Promotions Webinar going over details of the various promotions and add-ons.

Presentations
10/14/2026
2027 Promotions Webinar Slides

Slides for the 2027 Promotions Webinar providing details on the various promotions offered.

Release Notes
10/14/2026
EU Customs Change Release Overview
Technical Specifications
10/14/2026
USPS MCAT - TechSheet
Announcements
10/13/2026
PROCESSING & DISTRIBUTION: Update - Hurricane Isaias - Gulf Region of U.S. - Processing Facilities Resume Operations
Announcements
10/13/2026
DELIVERY: Update - Southern Area - Florida 1 - 3 Digit Zip Code Areas - 324 & 325 Operations Restored
Release Notes
10/13/2026
October 11 2026 EPS 8.7.2.0 Release Notes