Contact Lists
08/13/2026
CASS™ Certified Products Guide: Vendor/Service Licensees Data File Cycle O - (Expires July 31, 2028)
Contact Lists
08/13/2026
CASS™ Certified Products Guide: Vendor/Service Bureaus Licensees Cycle O - (Expires July 31, 2028)
Contact Lists
08/13/2026
CASS™ Certified Products Guide: DSF2® Licensees Data File Cycle O - (Expires July 31, 2028)
Contact Lists
08/13/2026
DSF2® Licensees Cycle O: Certified Products Guide - (Expires July 31, 2028)
Contact Lists
08/13/2026
DPV® Licensees Data File Cycle O: Certified Products Guide (D) - (Expires July 31, 2028)
Contact Lists
08/13/2026
DPV® Licensees Cycle O: Certified Products Guide - (Expires July 31, 2028)
Contact Lists
08/13/2026
CASS™ Software Manufacturers Data File Cycle O: Certified Products Guide (D) - (Expires July 31, 2028)
Contact Lists
08/13/2026
CASS™ Software Manufacturers Cycle O - (Expires July 31, 2028)
Contact Lists
08/13/2026
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
08/13/2026
Z4 Info File

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

Data Files
08/13/2026
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
08/12/2026
INFORMATIONAL - USPS APIs System Release Notification – August 31, 2026
Announcements
08/12/2026
DELIVERY - La Villa Post Office (78562) - Temporarily Suspended
Announcements
08/12/2026
DELIVERY: WestPac Area - NV-UT District - Nixon Post Office (89424) - Office Temporarily Closed
Applications/ Forms
08/12/2026
Request to Lead or Participate - MTAC User Group and Work Group
FAQs
08/12/2026
USPS PTR2 API Known Issues
Contact Lists
08/12/2026
Mailers Technical Advisory Committee (MTAC) Membership Roster and Vacancies
Release Notes
08/12/2026
USPS APIs Release Notes

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

Presentations
08/11/2026
Pop-Up Mini Cafe: Part Two - Informed Delivery for PCCs
 
Contact Lists
08/11/2026
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

 

FAQs
08/10/2026
Modernization of Address Processing with APIs - Q & A
Fact Sheets
08/10/2026
USPS Addresses API - Completing PS Form 3553
Announcements
08/10/2026
INFORMATIONAL - Commercial System Releases – Week of August 15, 2026
Announcements
08/10/2026
INFORMATIONAL - PostalOne! Release – August 16, 2026
Release Notes
08/10/2026
August 9, 2026 Program Registration R31.1.0.0 Release Notes