Release Notes
06/27/2026
PTR2 Release Notes_DD_06_27_26
Announcements
06/26/2026
DELIVERY: Southern Area -Louisiana District - Dupont Post Office (71329) - Temporarily Suspended
Announcements
06/26/2026
PROCESSING AND DISTRIBUTION: Louisville, KY - Region Modernization
Announcements
06/26/2026
PROCESSING & DISTRIBUTION: USPS Launches Three Regional Processing & Distribution Centers (RPDCs) on June 29, 2026
Release Notes
06/26/2026
USPS APIs Release Notes

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

Error Codes
06/25/2026
Known Issues List 6.25.2026
Contact Lists
06/25/2026
CASS™ Certified Products Guide: Residential Delivery Indicator Cycle O - (Expires July 31, 2028)
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06/25/2026
RDI™ Cycle O: Certified Products Guide (D) - (Expires July 31, 2028)

This document outlines the CASS/MASS certified vendors list for RDI™ Cycle O.

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06/25/2026
CASS™ Certified Products Guide: M L O C R Mailers/Users Data File Cycle O - (Expires July 31, 2028)
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06/25/2026
CASS™ Certified Products Guide: M L O C R Mailers/Users Cycle O - (Expires July 31, 2028)
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06/25/2026
CASS™ Certified Products Guide: M L O C R Service Bureaus Data File Cycle O - (Expires July 31, 2028)
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06/25/2026
CASS™ Certified Products Guide: M L O C R Service Bureaus Cycle O - (Expires July 31, 2028)
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06/25/2026
CASS™ Certified Products Guide: M L O C R Hardware Manufacturers Data File Cycle O - (Expires July 31, 2028)
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06/25/2026
CASS™ Certified Products Guide: M L O C R Hardware Manufacturers Cycle O - (Expires July 31, 2028)
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06/25/2026
CASS™ Certified Products Guide: Z4CHANGE Data File Cycle O - (Expires July 31, 2028)
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06/25/2026
CASS™ Certified Products Guide: Z4CHANGE Cycle O - (Expires July 31, 2028)
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06/25/2026
CASS™ Certified Products Guide: Vendor/Service Licensees Data File Cycle O - (Expires July 31, 2028)
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06/25/2026
CASS™ Certified Products Guide: Vendor/Service Bureaus Licensees Cycle O - (Expires July 31, 2028)
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06/25/2026
CASS™ Certified Products Guide: DSF2® Licensees Data File Cycle O - (Expires July 31, 2028)
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06/25/2026
DSF2® Licensees Cycle O: Certified Products Guide - (Expires July 31, 2028)
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06/25/2026
DPV® Licensees Data File Cycle O: Certified Products Guide (D) - (Expires July 31, 2028)
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06/25/2026
DPV® Licensees Cycle O: Certified Products Guide - (Expires July 31, 2028)
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06/25/2026
CASS™ Software Manufacturers Data File Cycle O: Certified Products Guide (D) - (Expires July 31, 2028)
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06/25/2026
CASS™ Software Manufacturers Cycle O - (Expires July 31, 2028)
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06/25/2026
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.