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.

Informed Visibility® Mail Tracking & Reporting (IV®-MTR) Release Notes

These release notes summarize new features and enhancements implemented in deployments to the IV-MTR application.

NCOALink® Limited Service Provider Licensees

This document provides a list of service providers and contact information for NCOA^Link®. These providers receive 18 months of change-of-address (COA) data on a weekly basis from the USPS^®. For the full 48 months of COA data refer to the NCOA^Link Full Service Provider Licensees.

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.

DELIVERY - El Portal Post Office – Resume Operations

INFORMATIONAL - USPS APIs System Release Notification - September 16, 2026

Informed Visibility Mail Tracking & Reporting Machine Count

List of US Postal Service machines by site, including a description of each machine.

ZIP Codes by Area and District codes

The Excel spreadsheet lists ZIP Codes with the associated Area and District Codes.