INFORMATIONAL - UPDATE - Commercial System Releases – Week of September 12, 2026

Request to Lead or Participate - MTAC User Group and Work Group

PCCAC Certification Webinar: Address Hygiene with Adam Collinson

INFORMATIONAL - 2027 National Postal Forum Registration Now Open

PCC Alert: 2027 National Postal Forum Registration Now Open

Informed Visibility® Mail Tracking & Reporting (IV®-MTR) Development Tracker

This document provides a list of active IV-MTR work to be as well as items completed in the current fiscal year.

*Please note, Postal Pro is the only source for a current IV-MTR Development log as updates will be made on an ongoing basis.

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.

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.  

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

Automated Zone Indicator (AZI) Table

The AZI table lists each five-digit ZIP Code™ and is an indicator of the type of processing that typically takes place on letter mail destined for each ZIP Code. Each number in the file is a ZIP Code appended with a numeric zone indicator. The five numeric indicators are as follows:

1. Two Pass Zones: Automated two-step sector/segment at mail processing facilities
2. 876 Carrier Route Sort Zones: Automated incoming secondary carrier route sorting at plants
3. Carrier Route Barcode Sorter (CSBCS) Zones: Automated walk sequence sorting on CSBCS machines at delivery units
4. Delivery Barcode Sorter (DBCS) Zones: Automated walk sequence sorting on DBCS machines at plants [i.e., sectional center facilities (SCFs)] or at delivery units
5. Manual/Mechanized Zones: No automated sorting; no tracking code scans should be generated from facilities matched to these ZIP Codes

City/State ZIP Code Weekly Compare

Area District Finance File Specification (AREA_DIST_LAYOUT.TXT)