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 - Postal Service Updates for May and June 2026 - SDC Activations

DELIVERY - Diplomatic Post Office (09291) to resume Mailing Services

PTR2 Release Notes_DD_04_23_26

INFORMATIONAL - July 2026 Market Dominant Price Change Filing Webinar Posted to PostalPro

July 2026 Market Dominant Price Change Filing Webinar

Overview of July 2026 Market Dominant Price Change.

If you missed the session—or would like to revisit this informative presentation—you can access both the presentation slides and the full webinar recording at the link below:

To view Webinar click here:

Passcode: WQ!!7t=8

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.

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.

INFORMATIONAL - USPS APIs System Notification April 23, 2026