Skip to main content

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. 

Who is Traditional ACS for?

First Class Mail
Standard Mail


Traditional ACS is the original version of ACS that was developed for Periodical mailers and was eventually expanded to include all mail classes. It allows customers that mail letters, flats or parcels, of all mail classes to receive electronic address corrections.

Traditional ACS contains the following lines of data in addition to the usual delivery and return addresses:

  1.  The Ancillary Service Endorsement provides the Postal Service™ with the sender's instructions on how to handle the mail if it is UAA.
  2. The Traditional ACS Participant ID/Code is preceded by a pound sign (#) and identifies the sender to the Postal Service.
  3. The Traditional ACS Keyline is delimited by pound signs and identifies the recipient in the sender's mailing list. The Traditional ACS keyline is required to receive NIXIE notices.
  4. The Intelligent Mail® barcode applied to the mail may contain presort information (flats only), a Service Type Identifier that requests specific services like ACS and/or IMb Tracing, a Mailer ID that identifies the mail owner or mail service provider, a serial or sequence number that uniquely identifies the mail piece, and routing information that provides the ZIP Code and delivery point validation that allows the mail to be sorted directly to the address.


Traditional ACS mail must meet all of the addressing requirements found in the Domestic Mail Manual (DMM) 602.

All Traditional ACS mailpieces, as with all mail requesting ancillary services, must have a domestic Return Address properly appearing on the front of the mailpiece.

Internet Access

Customers must have the ability to retrieve ACS Fulfillments electronically from the USPS® Electronic Product Fulfillment (EPF) website.

Participant ID

To use Traditional ACS, you must add the ACS Participant ID (also known as the Participant Code) assigned by the Postal Service™ to the address block of your mailpiece. This code can be provided only by the ACS Department at the NCSC. A Participant ID is assigned for a specific class of mail and consists of seven alpha characters, with the first character as the letter “B”. It must be printed in uppercase on the mailpiece or first line of the address block, aligned left, and preceded by a single pound sign (#) delimiter. If printed on the OEL, the Participant ID must be followed by at least one space before any further information (carrier route, presort level, etc.) is printed on that line.

The following DMM references provide information regarding Traditional ACS Participant ID requirements.

  • DMM 507.4.2.3a for Participant ID description and placement requirements
  • DMM 507.4.2.5 for Participant ID and ancillary service endorsement placement requirements
  • DMM 708.7.2.3 when printing the Participant ID in the Optional Endorsement Line (OEL)


All ACS mailpieces mailed at automation rates must meet all requirements for barcodes set forth in the DMM. If you print the Intelligent Mail barcode in the address block, three locations are acceptable:

  1. When using the optional keyline, place the barcode between the top line of the address information and the mailer keyline. When not using a mailer keyline, place the barcode between the top line of the address information and the Participant ID.
  2. Below the City-State-ZIP Code line.
  3. Above the Participant ID/OEL (except when printing the Participant ID on the envelope as described in DMM 507.4.2.5f).

IMPORTANT NOTE: A traditional keyline is required to receive NIXIE notices. If you utilize an Intelligent Mail barcode for discounts only and continue to request Traditional ACS, the appropriate Service Type ID (STID) must be used in the IMb to request Traditional ACS. For a current list of the Traditional ACS Service Type IDs refer to the Table of Service Type Identifiers.

No vendor information posted for this page yet.

Featured Resources

ACS™ Technical Guides

ACS™ Forms

ACS™ Test Files and Tools

ACS™ Resources

Related Products

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.

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.


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.


ACS customers are required to provide a dedicated email address to receive communications regarding ACS. If your company or organization does not currently have a dedicated email for this purpose, we request that you establish one, preferably using the following format:

All appropriate parties should be designated as users of this email account. It is the responsibility of your company to monitor and control dissemination of this information to your internal ACS decision makers.

Hide from Site-Index? (Check for yes)