NPF Call for Presentations Closing 10/30/2026

INFORMATIONAL - PostalOne! System – Issues with Promotion Removal and Auto-Finalized Postal Wizard Statements

INFORMATIONAL - NPF 2027 Call for Presentations is closing on Friday, October 30th

2026 Promotions FAQ

USPS APIs Release Notes

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

CASS™ Certified Products Guide: Residential Delivery Indicator Cycle O - (Expires July 31, 2028)

RDI™ Cycle O: Certified Products Guide (D) - (Expires July 31, 2028)

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

CASS™ Certified Products Guide: M L O C R Mailers/Users Data File Cycle O - (Expires July 31, 2028)

CASS™ Certified Products Guide: M L O C R Mailers/Users Cycle O - (Expires July 31, 2028)

CASS™ Certified Products Guide: M L O C R Service Bureaus Data File Cycle O - (Expires July 31, 2028)

CASS™ Certified Products Guide: M L O C R Service Bureaus Cycle O - (Expires July 31, 2028)

CASS™ Certified Products Guide: M L O C R Hardware Manufacturers Data File Cycle O - (Expires July 31, 2028)

CASS™ Certified Products Guide: M L O C R Hardware Manufacturers Cycle O - (Expires July 31, 2028)

CASS™ Certified Products Guide: Z4CHANGE Data File Cycle O - (Expires July 31, 2028)

CASS™ Certified Products Guide: Z4CHANGE Cycle O - (Expires July 31, 2028)

CASS™ Certified Products Guide: Vendor/Service Licensees Data File Cycle O - (Expires July 31, 2028)

CASS™ Certified Products Guide: Vendor/Service Bureaus Licensees Cycle O - (Expires July 31, 2028)

CASS™ Certified Products Guide: DSF2® Licensees Data File Cycle O - (Expires July 31, 2028)

DSF2® Licensees Cycle O: Certified Products Guide - (Expires July 31, 2028)

DPV® Licensees Data File Cycle O: Certified Products Guide (D) - (Expires July 31, 2028)

DPV® Licensees Cycle O: Certified Products Guide - (Expires July 31, 2028)

CASS™ Software Manufacturers Data File Cycle O: Certified Products Guide (D) - (Expires July 31, 2028)

CASS™ Software Manufacturers Cycle O - (Expires July 31, 2028)

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.

Z4 Info File

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

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.

INFORMATIONAL - USPS APIs System Deployment November 14

INFORMATIONAL - USPS APIs System Deployment November 8

INFORMATIONAL - USPS APIs System Deployment November 1

INFORMATIONAL - USPS APIs System Deployment - November 1

INFORMATIONAL - USPS APIs System Release Notification November 5

INFORMATIONAL -Informed Visibility USPS Ship Subscription Delays During Daylight Savings Time

DELIVERY - International Resumption of Mail Service Argentina - Effective October 30, 2026

Known Issues List 10.27.2026

USPS Ship Disputes and Refunds: Joint Review

USPS Ship Frequently Asked Questions

USPS Ship Frequently Asked Questions

Informed Visibility® Mail Tracking & Reporting (IV®-MTR) Operation Codes List

This spreadsheet provides a list of operation codes (opcodes), also known as Scan Event Codes, for the IV-MTR application.

INFORMATIONAL: USPS APIs System Release Notification - Ship 30.0.1.0 Release

INFORMATIONAL - November 9-13 Recommendations for Live Animal Shipping

INFORMATIONAL - RESOLVED - PostalOne! System – INCIDENT 11152094

PTR1 Maintenance Notes_DD_10_31_26

Labeling List Changes Effective December 1, 2026

Effective December 1, 2026, the Postal Service™ will revise Labeling List(s) L001, L004, L009, L010, L012, L015, L016, L201, L602, L605, and L606 to reflect changes in mail processing operations. Mailers are expected to label according to these revised lists for mailings inducted on or after the December 1, 2026, effective date through January 31, 2027, expiration date. The changes will be published in the Postal Bulletin, Issue #22715.
 

***Updated - New Areas*** - Area District 5-digit ZIP Codes (AREADIST_ZIP5.TXT)

City/State ZIP Code Weekly Compare

3 Digit ZIP/AISU Office List (AISUREPT.TXT)

AIS Congressional District File (CONG_DIST.TXT)

AIS County Name Table Layout (AISCNTY.TXT)

AMS County Name Table (COUNTY_NAME_TABLE.TXT)