Contact Lists
01/22/2026
CASS™ Software Manufacturers Cycle O - (Expires July 31, 2028)
Contact Lists
01/22/2026
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.

Data Files
01/22/2026
Z4 Info File

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

Data Files
01/22/2026
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.

 

Data Files
01/21/2026
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.

Contact Lists
01/21/2026
Publication 205 eVS Electronic Verification System Pre-certified

Software certified for mailers to use eVS for parcel shipping:

*Precertified for file format.

*Precertified for labels. 

Announcements
01/20/2026
INFORMATIONAL: PostalOne! System (PO!) – [INCIDENT # 10342990] Mail.dat, Mail.XML and Shipping Services Files (PO! eVS) Processing Delay
Release Notes
01/20/2026
01_20_25_PTR2 Release Notes
Announcements
01/20/2026
Engage with Us at the Strategic Innovation Pop-Up Mini-Cafe!
Announcements
01/20/2026
INFORMATIONAL - Postal Service Opens Bid Solicitation Platform For Entry to Last-Mile Delivery