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 Modernization Through Package Equipment Upgrades in April 2026

INFORMATIONAL - Atlantic Area AIM Meeting June 2, 2026

March 2026 Nixie Volume

This spreadsheet contains the UAA statistics for March 2026.

INFORMATIONAL - Federal Register - Manifest Mailing System Retired April 1, 2026

Informed Visibility Mail Tracking & Reporting Machine Count

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

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 FY25.

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

ZIP Codes by Area and District codes

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

Pop-Up Mini Café: Brewed for Business: The Shipping Mini Café

Pop-Up Mini Café: Brewed for Business: The Shipping Mini Café

Passcode: 5T8K2$*L

DELIVERY - Southern Area - Puerto Rico District - Moca Post Office (00676) - Suspended

INFORMATIONAL - USPS Package Tracking Access Control Implementation (Effective Wednesday, April 1, 2026)

DELIVERY - Atlantic Area Easton Post Office (18042) - Closed Until Further Notice

INFORMATIONAL: Mail Spoken Here March 2026 Issue

INFORMATIONAL - USPS APIs System Maintenance April 15 Release

USPS APIs Terms and Conditions

ACKNOWLEDGEMENT AND ACCEPTANCE. Read this carefully before registering to use the USPS API services. By utilizing the APIs, you hereby ACCEPT ALL of the terms and conditions of this Agreement. 

USPS PTR2 API Known Issues

***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)

AMS Address Report: AISU Mailing List (ADDRREPT.TXT)

AISU ZIP Code Record and AISU Address Record Descriptions (AISULOUT.TXT)