Contact Lists
07/09/2026
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.

Announcements
07/08/2026
INFORMATIONAL - Upcoming USPS.com Maintenance July 11th Cancelled
Fact Sheets
07/08/2026
Addresses API - Tech Sheet
Program Requirements
07/08/2026
2026 Promotions FAQ
Announcements
07/07/2026
PROCESSING AND DISTRIBUTION - Central Region - Saint Louis, MO - Weather Related Impacts
Announcements
07/07/2026
INFORMATIONAL - Update Commercial System Releases July 11 – July 17
Announcements
07/07/2026
INFORMATIONAL - USPS APIs System Release Notification - July 9, 2026
Announcements
07/07/2026
INFORMATIONAL - Update Domestic HAZMAT Handling and Noncompliance
Announcements
07/06/2026
DELIVERY - WestPac Area – CO-WY District Coal Creek CO and Rockvale CO Offices Temporarily Closed
Announcements
07/06/2026
INFORMATIONAL: Commercial System Releases - July 9, 2026