Publications
04/15/2026
Appendix B: ACS™ Frequently Asked Questions

This document provides frequently asked questions (FAQs) and answers about the Intelligent Mail® Barcode, Traditional ACS™, OneCode ACS™, Full Service ACS™, Single Source ACS™, and the Intelligent Mail® Package Barcode (IMpb).

Announcements
04/14/2026
INFORMATIONAL -PostalOne! System - INCIDENT 10567141 Error with Mail Entry Additional Postage Assessment Report
Announcements
04/14/2026
INFORMATIONAL - National Postal Forum 2026 Keynote Speaker – Jeremy Gutsche
Tech Guides
04/14/2026
USPS Ship Monthly Averages Tech Sheet
Announcements
04/13/2026
INFORMATIONAL - USPS Enhanced Addresses API – Coming July 2026
Announcements
04/13/2026
INFORMATIONAL - Informed Delivery Campaign Reporting Update April 2026
Applications/ Forms
04/13/2026
Addressing API License Agreement
Announcements
04/13/2026
INFORMATIONAL - 2026 National Postal Forum Leadership Insight Sessions
Announcements
04/13/2026
INFORMATIONAL - Package Tracking API Provisioning Cancelled
Technical Specifications
04/13/2026
Mail.dat Technical Specifications R64.0.0.0