ACS is a post mailing service that allows mailers to receive change-of-address (COA) and other reasons for non-delivery electronically and reduce the number of manual (hardcopy) address notifications.

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Who is ACS for?

First Class Mail

First Class Mail





Standard Mail

Standard Mail


ACS has many benefits over manual address corrections.

ACS is a cost-effective, efficient means of obtaining accurate COA or reasons for non-delivery information. Utilizing ACS can:

  1. Reduce manual address costs.
  2. Reduce labor-intensive address change functions by eliminating returned mail.
  3. Retrieve address change information electronically via a secure Internet site to allow automated updating of mailing lists.
  4. Receive notifications that relate specifically to their address files.

ACS has four distinct implementation methods which offer several different options:

  1. OneCode ACS Technical Guide contains information to participate in OneCode ACS® (uses IM® barcode).
  2. Traditional ACS Technical Guide contains information to participate in Traditional ACS®.
  3. Full-Service ACS, which is currently provided as an additional benefit for mail that qualifies for Full-Service discount postage prices (uses IM® barcode).
  4. IMpb ACS Technical Guide contains information to participate in IMpb ACS (uses IM® package barcode).

For a complete overview of Address Change Services including eligibility, benefits, implementation, and technical specifications please review the ACS™ Product Information Guide: Publication 8

To participate in ACS, mailers must modify their mailing label, address block, and mailpiece according to the requirements associated with the specific ACS service they are applying for.

As ACS-modified mailpieces are processed via Postal Automation Redirection System (PARS) or Computerized Forwarding System (CFS), ACS notifications are generated when possible. However, ACS is an enhancement to the traditional process of manual (hard copy) notifications and it does not completely replace or eliminate hard copy address change notifications.

The ACS notifications are transmitted to the National Customer Support Center (NCSC), where the notifications are consolidated into a file for the mailer. ACS fulfillment options vary depending on the specific ACS service you are applying for.

If you have not already opened an ACS account, contact the ACS Department at Check, credit card, ACH credit or CAPS payment options are available.

Featured Resources

Mailer's Technical Advisory Committee - Best Practices for ACS™

This document is designed to enhance mailers' understanding of the US Postal Service's ACS™ product.

Related Products

Traditional ACS™

Traditional ACS is one of the four ways to participate in ACS, where mailers notifications of undeliverable mail (UAA) and change-of-address (COA) electronically. The Intelligent Mail® barcode is not required to receive Traditional ACS.

OneCode ACS®

OneCode ACS allows customers mailing First-Class Mail®, Standard Mail®, and Periodical flats or letters to receive electronic or automated address corrections using the Intelligent Mail® barcode.

SingleSource ACS™

SingleSource ACS™ removes the need for handling different file formats when dealing with Full Service ACS, OneCode ACS®, IMpb ACS and Traditional ACS. With SingleSource ACS, all of the ACS notices are combined into a single file format and are provided via Electronic Product Fulfillment (EPF).

Intelligent Mail® Package Barcode (IMpb) ACS™

IMpb ACS allows parcel mailers who print the Intelligent Mail package barcode to receive an electronic address correction using that barcode.

Ancillary Service Endorsements

Ancillary Service Endorsements allow for a sender to obtain an addressee’s forwarding/new address if the addressee has filed a Change-of-Address order with the Postal Service, or a reason for why a mailpiece has not been delivered.

Secure Destruction

Secure Destruction is a cost effective, secure, and convenient way to manage mail with personal protected information.


The NCOALink Product is a secure dataset of approximately 160 million permanent change-of-address (COA) records consisting of names and addresses of individuals, families and businesses who have filed a change of address with the Postal Service™. Developed with secure data store technology to increase security of postal customer data and protect the privacy of this information, the NCOALink Product enables mailers to process mailing lists and update lists with new addresses prior to mailing. The NCOALink data is provided on a regular basis to companies that have been licensed by the Postal Service.


Questions? Get in touch. 

While the ACS Department can assist customers with questions, it is beneficial for all customers to read specific ACS service documentation and consolidate any questions. You may email the questions and schedule conference calls by calling 877-640-0724, option 1 or email us at