Fact Sheets
03/03/2026
Ancillary Service Endorsement Fact Sheet

Ancillary service endorsements are used by mailers to request an addressee’s new address or the reason mail cannot be
delivered as addressed and to provide the US Postal Service with instructions on how to handle Undeliverable As Addressed
(UAA) mailpieces.

Fact Sheets
02/12/2026
Manifest Mailing Systems Retirement Fact Sheet

The USPS is amending Mailing Standards of the United States Postal Service, Domestic Mail Manual (DMM) subsection 703.2.0 to retire the manifest mailing system (MMS). Effective April 1, 2026.

Fact Sheets
12/18/2025
Addressing Fact Sheet for First-Class Flats

This document is for mailers who are sending flat-size mail (such as large envelopes) at Automation and Presorted First-Class Mail prices. To use these prices, you must mail at least 500 pieces at a time, prepared and sorted according to Postal Service guidelines.