10/30/2025
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.
10/30/2025
Z4 Info File
A downloadable ZIP file containing information related to the Z4 Info File
10/30/2025
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.
10/29/2025
10/29/2025
10/29/2025
10/28/2025
10/28/2025
10/27/2025
Properly Securing Bundles of Flats
Please note that as of July of 2025, the Postal Service no longer permits using rubber bands and twine or string for securing bundles of flats, with the exception of bundles of First-Class Mail® flats placed in flat trays. All bundles of flats must have two or more cross-strapped bands or be shrink-wrapped with one or more cross-strapped bands, with the exception of newspapers that are placed in a flat tray and entered as exceptional dispatch. Such newspapers may be bundled by using only one strap around the middle of the bundle to prevent damage.
10/27/2025