Undeliverable mail: forwarding, endorsements and ACS

What does Return Service Requested mean on a piece of mail?

Return Service Requested is an ancillary service endorsement asking USPS to return an undeliverable piece with the new address or reason for nondelivery attached.5Guide to Move Updatepage 5“Return Service Requested: The mailpiece is returned with the new address information or reason for nondelivery affixed.”USPS original USPS does not forward the piece, even when the addressee has filed a change-of-address order.5Guide to Move Updatepage 5“No forwarding service is provided.”USPS original6Publication 32: Glossary of Postal Termspage 193“A general designation for undeliverable-asaddressed mail that cannot be forwarded because no active change-of-address order is on file or because the sender has endorsed the mail “Return Service Requested” and an active change-of-address order is on file.”USPS original First-Class Mail comes back at no charge, while a USPS Marketing Mail mailer pays a single-piece price for each returned piece.5Guide to Move Updatepage 5“The return of First-Class Mail is provided at no charge.”USPS original7DMM 507: Mailer Services“The mailer of a returned piece endorsed “Return Service Requested” is charged the applicable single-piece First-Class Mail or USPS Ground Advantage – Retail price for the weight and shape of the piece, and the nonmachinable surcharge if applicable.”USPS original

What does Change Service Requested mean on an envelope?

Change Service Requested asks USPS to discard an undeliverable piece and send the mailer a notice of the new address or reason for nondelivery.5Guide to Move Updatepage 5“Change Service Requested: A separate notice of new address or reason for nondelivery is provided and the manual address correction fee is charged. … The Postal Service disposes of the mailpiece.”USPS original First-Class Mail may carry it only with the electronic Address Change Service.5Guide to Move Updatepage 5“This endorsement is not available for First-Class Mail unless used in conjunction with electronic ACS.”USPS original Its second option forwards the piece during the first 12 months of a change-of-address order instead.8Guide to Move Updatepage 41“Same as Option 1, but mail will be forwarded for a change-of-address during months 1 through 12.”USPS original

What does Forwarding Service Requested mean on an envelope?

Forwarding Service Requested asks USPS to forward a piece to the addressee's new address where forwarding is not normally provided.5Guide to Move Updatepage 5“It is used only to request forwarding where forwarding service is not normally provided.”USPS original It asks for no address correction, so it does not meet the Move Update standard.5Guide to Move Updatepage 5“That is because this endorsement does not request address corrections. … Note that Forwarding Service Requested is not listed as a move update compliant ancillary service endorsement.”USPS original On USPS Marketing Mail, the mailer generally pays the weighted fee, a single-piece price times 2.472, on every piece that comes back.7DMM 507: Mailer Services“When forwarding service is provided, generally the mailer of USPS Marketing Mail is subject to paying additional postage: the USPS Marketing Mail weighted fee on all returns. … The weighted (per piece) fee is the First-Class Mail, USP Ground Advantage — Retail, or Priority Mail single-piece price and any nonmachinable surcharge … multiplied by 2.472, rounding any fractions to the next whole cent.”USPS original

Can presorted First-Class Mail be forwarded or returned to sender?

Yes, the default for undeliverable First-Class Mail is to forward it or return it to the sender.3Guide to Move Updatepage 28“For First-Class Mail, the default treatment for mailpieces that cannot be delivered as addressed is either for the mailpiece to be forwarded or to be returned to the sender.”USPS original With no ancillary service endorsement, USPS forwards the piece at no charge during months 1 through 12 of a change-of-address order.7DMM 507: Mailer Services“Same treatment as “Forwarding Service Requested.” … Months 1 through 12: Piece forwarded (no charge).”USPS original Without an order on file, the piece comes back with the reason for nondelivery attached, also at no charge.7DMM 507: Mailer Services“Piece returned with reason for nondelivery attached (no charge).”USPS original

Can USPS Parcel Select be forwarded to another address?

Yes, USPS forwards Parcel Select as postage due to the addressee during the first 12 months of a change-of-address order.7DMM 507: Mailer Services“Months 1 through 12: Package Services forwarded postage due at the single-piece price for the class of mail. … Parcel Select forwarded as postage due to addressee at the Ground Advantage – Commercial price plus the additional service fee.”USPS original It goes only to domestic addresses, and the addressee may refuse it.7DMM 507: Mailer Services“Package Services and Parcel Select mail is forwarded only to domestic addresses. … The addressee may refuse any piece of Package Services or Parcel Select that has been forwarded.”USPS original Shipper Paid Services lets the shipper pay the forwarding postage instead, which makes a refusal less likely.9Traditional ACS™ with Shipper Paid Services Technical Guidepage 7“Shipper Paid Service provides an option for the shipper to pay the forwarding postage via the ACS account, minimizing the chance that the parcel will be refused.”USPS original

Why is my mail being returned as undeliverable as addressed?

USPS returns mail it can't deliver as addressed when its mail class allows, and marks each piece with the reason, such as an incomplete, illegible or incorrect address.7DMM 507: Mailer Services“Mail that is undeliverable as addressed is forwarded, returned to the sender, or treated as dead mail, as authorized for the particular class of mail. … Undeliverable-as-addressed mail is endorsed by the USPS with the reason for nondelivery … Incomplete, illegible, or incorrect address.”USPS original Mail at a correct address is undeliverable too when the addressee is unknown there, has moved or died, refuses it, or leaves it unclaimed.7DMM 507: Mailer Services“Addressee not at address (unknown, moved, or deceased). … Mail refused by the addressee at time of delivery. … Mail unclaimed.”USPS original The Address Change Service reports such reasons to mailers electronically, such as Attempted Not Known.10Mailer's Technical Advisory Committee - Best Practices for ACS™page 39“ACS provides electronic notification for two different types of Undeliverable-as-Addressed (UAA) mail situations; either there is a COA on file, or the mail is determined to be UAA for a reason other than a move (i.e. Attempted Not Known, No Such Number, Unable To Forward/Forwarding Time Expired).”USPS original A correct-looking address can still come back after a USPS adjustment, such as renumbered houses or a renamed street.7DMM 507: Mailer Services“Mail can be undeliverable because of USPS adjustments such as the following: … a. Renumbering of houses. … b. Renaming of streets.”USPS original A carrier may also have delivered a wrongly addressed piece for years, knowing where it goes; a new carrier without that knowledge marks it undeliverable, such as No Such Number or No Such Street.11Mailer's Technical Advisory Committee - Best Practices for ACS™page 29“For example, Letter Carrier A has the knowledge to complete the delivery of a particular mail piece that has an incorrect primary number or street name and could have been doing so for years. … Carrier A retires, goes on vacation, or changes routes. Carrier B takes over and does not have the same knowledge. … New Carrier B determines this mail to be UAA and identifies it as a Nixie because there is No Such Number or No Such Street.”USPS original

What happens if USPS cannot deliver a package?

USPS forwards an undeliverable package, returns it to the sender or discards it, depending on its mail class, the sender's endorsement and any change-of-address order.2Intelligent Mail® Package Barcode (IMpb) ACS™ Technical Guidepage 10“The mail class (USPS Ground Advantage, Periodical, USPS Marketing Mail™, or Package Services/Parcel Select), the mailer’s requested ACS ancillary service, and the age or existence of a COA determines whether the parcel is forwarded, discarded, or returned to sender.”USPS original A package that can be neither delivered nor returned goes to the local Post Office or the USPS Mail Recovery Center.12Ancillary Services for Parcel Select and Parcel Select Lightweight FAQsPDF page 2“Undeliverable mailpieces are letters, flats or parcels that cannot be delivered as addressed nor returned to the sender. … These mailpieces are either handled by the local Post Office™ or sent to the USPS® Mail Recovery Center (MRC).”USPS original Contents worth more than $25.00 are held for 60 days when the package is barcoded, or 30 days when it is not.12Ancillary Services for Parcel Select and Parcel Select Lightweight FAQsPDF page 2“Undeliverable mail determined to be of value, meaning the content is worth more than $25.00 ($20.00 for mailpieces containing cash), will be held for 60 days if the mailpiece is barcoded, or 30 days for non-barcoded mailpieces.”USPS original

What does USPS Address Service Requested mean?

Address Service Requested asks USPS to forward the piece when possible and send the mailer a separate notice of the new address, for a fee.13Guide to Move Updatepage 4“Address Service Requested: The mailpiece is forwarded to the new address when possible and a separate notice with the new address is sent to the mailer and the manual address correction fee is charged.”USPS original A piece that cannot be forwarded comes back with the reason it could not be delivered.13Guide to Move Updatepage 4“If mail cannot be forwarded, it is returned with the reason it cannot be delivered.”USPS original USPS does not recommend it for USPS Marketing Mail, whose returned pieces pay the weighted fee.13Guide to Move Updatepage 4“This endorsement is not recommended for USPS Marketing Mail because the Weighted Fee is charged for returned mail, which is equal to the comparable First-Class Mail postage, plus any non-machinable surcharges, multiplied by 2.472.”USPS original

USPS forwards mail that is undeliverable as addressed, returns it to the sender, or treats it as dead mail, as each mail class allows.7DMM 507: Mailer Services“Mail that is undeliverable as addressed is forwarded, returned to the sender, or treated as dead mail, as authorized for the particular class of mail.”USPS original Forwarding needs a change-of-address order from the addressee.1OneCode ACS® Technical Guide page 11“The USPS® can forward mail or notify mailers of a Change of Address (COA) only if the customer submits a change of address request with the Postal Service™.”USPS original By default, USPS Marketing Mail is disposed of instead.3Guide to Move Updatepage 28“For USPS Marketing Mail and Bound Printed Matter, the default treatment of UAA mail is to dispose of it.”USPS original Secure Destruction, an opt-in service, shreds undeliverable First-Class Mail letters and flats that hold personal information instead of returning them.14PostalPro: Secure Destruction“Part of the USPS® BlueEarth sustainability initiatives and an opt-in service, this new program securely shreds and recycles letter and flat-sized pieces of Undeliverable-As-Addressed (UAA) First-Class Mail® with personal protected information that would otherwise be returned to the sender (RTS).”USPS original A business can also have all its mail forwarded for a time through Premium Forwarding Service Commercial.15PostalPro: Premium Forwarding Service Commercial®“Premium Forwarding Service Commercial™ (PFSC) allows business customers with an active P.O. Box or street address to temporarily forward all mail to their domestic address using Priority Mail Express® or Priority Mail®.”USPS original

A mailer asks for other treatment with an ancillary service endorsement printed on the piece.16Guide to Move Updatepage 29“Ancillary Service Endorsements are printed on a mailpiece and recognized by the Postal Service when processing UAA mail.”USPS original The endorsement can also ask for a notice of the new address or the reason for nondelivery.7DMM 507: Mailer Services“A mailer endorsement is used to request forwarding, return, or address correction service.”USPS original Without electronic service, that notice is a PS Form 3547 or the returned piece itself.17A Guide to Full Servicepage 14“When an ASE is used without an ACS, either a hard copy address correction (PS Form 3547 or 3579) or the return of the piece fulfills the mailer's request.”USPS original Endorsements and the Address Change Service are the post-mailing methods of Move Update, the USPS standard for matching mailers' address records with change-of-address orders.18Guide to Move Updatepage 14“Of the primary methods, NCOALink including NCOALink MPE are known as “pre-mailing” methods; ACS and Ancillary Service Endorsements are known as “post mailing” methods.”USPS original19Guide to Move Updatepage 13“The Move Update standard is a means of reducing the number of mailpieces in a mailing that require forwarding or return by the periodic matching of a mailer’s address records with change-of-address orders received and maintained by the Postal Service.”USPS original

The Address Change Service, or ACS, sends these notices electronically, and it has four kinds.4PostalPro: ACS™“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.”USPS original20OneCode ACS® Technical Guide page 7“ACS has four distinct implementation methods OneCode ACS, Full Service ACS, IMpb ACS and Traditional ACS.”USPS original

• Traditional ACS reads a Participant ID printed in the address block.21Traditional ACS™ Technical Guidepage 8“Participation in Traditional ACS requires the mailer to include the USPS assigned Participant ID and optional keyline in the address block on the mailpiece (see Exhibit 1).”USPS original
• OneCode ACS reads the Intelligent Mail barcode on letters and flats.22OneCode ACS® Technical Guide page 8“OneCode ACS allows customers mailing First-Class Mail®, USPS Marketing Mail™, and Periodical flats or letters to receive electronic or automated address corrections using the Intelligent Mail® barcode.”USPS original
• Full-Service ACS is OneCode ACS for Full-Service mail, which pairs a unique barcode on every piece, tray and container with electronic documentation.23Mailer's Technical Advisory Committee - Best Practices for ACS™page 4“Full-Service ACS is OneCode ACS for Full-Service mail”USPS original24Publication 685: Publication for Streamlined Mail Acceptance for Letters and FlatsPDF page 15“Full-Service combines the use of unique barcodes on each container, tray and mailpiece with electronic submission of postage statements and documentation.”USPS original
• IMpb ACS reads the Intelligent Mail package barcode on parcels.25PostalPro: 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.”USPS original

SingleSource ACS combines all of a mailer's notices into one file.4PostalPro: ACS™“With SingleSource ACS, all of the ACS notices are combined into a single file format and are provided via Electronic Product Fulfillment (EPF).”USPS original

What forwarding and return cost depends on the mail class.26Ancillary Services for Parcel Select and Parcel Select Lightweight FAQsPDF page 1“The endorsements are the same for all classes of mail, but the treatment and cost differ by class of mail.”USPS original Shipper Paid Services lets a parcel shipper pay forwarding or return postage through its ACS account instead of the customer.27PostalPro: Shipper Paid Services“Shipper Paid Services is an ACS fulfillment option that allows parcel mailers to receive an electronic address correction and pay forwarding or return postage via their ACS account rather than charging the customer.”USPS original

Post Offices keep a record of permanent change-of-address orders for 18 months.7DMM 507: Mailer Services“A record of permanent change-of-address orders is kept by Post Offices for 18 months, from the end of the month when the change takes effect.”USPS original Forwarding generally lasts for the first 12 of those months.7DMM 507: Mailer Services“Generally, forwarding is available for the first 12 months.”USPS original A temporary order forwards mail for no more than 12 months.7DMM 507: Mailer Services“A customer temporarily moving away may have mail forwarded for a specific period of time, not to exceed 12 months (364 total consecutive days).”USPS original USPS does not forward mail addressed to a commercial mail receiving agency.7DMM 507: Mailer Services“Mail addressed to an addressee at a commercial mail receiving agency (CMRA) is not forwarded through the USPS.”USPS original

What USPS does with an undeliverable piece by default depends on its mail class.26Ancillary Services for Parcel Select and Parcel Select Lightweight FAQsPDF page 1“The endorsements are the same for all classes of mail, but the treatment and cost differ by class of mail.”USPS original

USPS marks each piece it can't deliver as addressed with one of its own endorsements, each naming a reason for nondelivery, such as these.7DMM 507: Mailer Services“Undeliverable-as-addressed mail is endorsed by the USPS with the reason for nondelivery”USPS original

Mail with no specific address and no sender instructions is held 5 days on a rural or highway contract route.7DMM 507: Mailer Services“Mail without a specific address or instructions from the sender is held: … For 5 days if for delivery by rural or highway contract route carrier.”USPS original General delivery lets customers with proper identification pick up mail at a Post Office.29Publication 32: Glossary of Postal Termspage 93“An alternate delivery service that allows customers with proper identification to pick up mail at Post Offices.”USPS original Its mail is held 10 days at an office with city carriers and 15 days at one without.7DMM 507: Mailer Services“For 10 days if for general delivery at an office with city carrier service. … For 15 days if for general delivery at an office without city carrier service.”USPS original Deliverable mail for a Post Office box goes back only after the box is declared vacant, except mail such as Certified Mail.7DMM 507: Mailer Services“Deliverable mail addressed to a Post Office box is not returned until after the box is declared vacant, except for certified, collect on delivery (COD), insured, registered, postage due, Adult Signature and perishable mail.”USPS original

Certified Mail, Registered Mail and other signed-for mail goes back to the sender 15 days after a delivery notice if no one calls for it.30DMM 508: Recipient Services“The following conditions also apply to the delivery of Priority Mail Express, Registered Mail, Certified Mail, mail insured for more than $500.00, Adult Signature, or COD, as well as mail for which a return receipt is requested or the sender has specified restricted delivery. … If the piece is not called for or redelivery is not requested, the piece is returned to the sender after 15 days (5 days for Priority Mail Express, 10 days for COD), unless the sender specifies fewer days on the piece.”USPS original Priority Mail Express goes back after 5 days and COD after 10, unless the sender prints fewer days on the piece.30DMM 508: Recipient Services“If the piece is not called for or redelivery is not requested, the piece is returned to the sender after 15 days (5 days for Priority Mail Express, 10 days for COD), unless the sender specifies fewer days on the piece.”USPS original On other mail, a sender can ask for a hold of 3 to 30 days by printing it in the return address.7DMM 507: Mailer Services“At the sender’s request, the delivery Post Office holds mail, other than Registered Mail, Insured, Certified Mail, COD, Adult Signature, and Signature Confirmation, for no fewer than 3 days or more than 30 days. … A specific retention time of not less than 3 or more than 30 days, if requested, must be included by the sender in the return address on the mailpiece (e.g., “Return in 30 days to” followed by sender’s return address).”USPS original

Undeliverable letters and flats that automation can process go through the Postal Automated Redirection System, which has three modes.31Mailer's Technical Advisory Committee - Best Practices for ACS™page 30“There are 3 PARS modes of operation: Intercept (INT) – is available only for automation compatible letters. … PARS for Automation Letters and Flats will provide four possible results:”USPS original Its Intercept mode catches a letter sent to the old address on a change-of-address order and checks that the names match.31Mailer's Technical Advisory Committee - Best Practices for ACS™page 30“Letter automation has the ability to capture letter mail that is addressed to the OLD address of a COA, validate that the name on the mail matches the name on the COA, and redirect it without having to go to the carrier of the old address first.”USPS original A matched letter goes to a Combined Input Output Sub-System, a mail processing machine that prints a label to redirect it.31Mailer's Technical Advisory Committee - Best Practices for ACS™page 30“If a match is confirmed, the mail piece is directed to a PARS CIOSS (Combined Input Output Sub-System) that has image capture and character reading capability and has been retrofitted with a label applicator and printer so the mail can be redirected as needed.”USPS original Its Return to Sender mode handles mail that is undeliverable for reasons other than a change of address.31Mailer's Technical Advisory Committee - Best Practices for ACS™page 30“Return to Sender (RTS) – is the processing mode used for automation-compatible letter and flat mail that is undeliverable for reasons other than a COA.”USPS original The Computerized Forwarding System makes ACS data and manual notices for parcels and for letters and flats that automation can't process.31Mailer's Technical Advisory Committee - Best Practices for ACS™page 30“For OneCode ACS, Full-Service ACS, Traditional ACS, and IMpb ACS, CFS will generate ACS data and manual address correction notices for parcels and non-automation compatible letters and flats that cannot be processed by PARS or CFS.”USPS original

Dead mail is mail that USPS can neither deliver nor return to the sender.7DMM 507: Mailer Services“Dead mail is matter deposited in the mail that is undeliverable and cannot be returned to the sender.”USPS original Mail recovery centers open dead letters to find an address for delivery or return.7DMM 507: Mailer Services“Dead letters are opened at mail recovery centers to determine the name and address of the addressee or sender to permit delivery or return.”USPS original

Green & Secure is the set of ACS options that a Change Service Requested Service Type ID, a code in the piece's barcode, asks for.32Guide to Move Updatepage 42“Mailpieces bearing an ACS Change Service Requested Service Type ID is considered a Green & Secure option.”USPS original It lets USPS dispose of undeliverable pieces with or without secure destruction.32Guide to Move Updatepage 42“Green & Secure allows USPS to dispose of undeliverable mailpieces in one of two ways, either with or without secure destruction.”USPS original It covers First-Class Mail and USPS Marketing Mail letters and flats, but only First-Class Mail can use secure destruction.32Guide to Move Updatepage 42“It is available for First-Class Mail and USPS Marketing Mail letters and flats, however only First-Class Mail can utilize the secure destruction option.”USPS original Secure Destruction shreds those pieces, and mailers pay no extra fee to take part.31Mailer's Technical Advisory Committee - Best Practices for ACS™page 30“A First-Class Mail piece is sorted for Secure Destruction and the mail piece is shredded.”USPS original33Secure Destruction Frequently Asked Questions (FAQs)PDF page 1“There are no additional fees for mailer participation in this service.”USPS original

Premium Forwarding Service Commercial forwards all of a business's mail for a time to its domestic address, by Priority Mail Express or Priority Mail.15PostalPro: Premium Forwarding Service Commercial®“Premium Forwarding Service Commercial™ (PFSC) allows business customers with an active P.O. Box or street address to temporarily forward all mail to their domestic address using Priority Mail Express® or Priority Mail®.”USPS original The business pays an annual enrollment fee and postage for each shipment.15PostalPro: Premium Forwarding Service Commercial®“An annual enrollment fee is required, and applicable postage is charged for each shipment.”USPS original As of July 12, 2026, the online enrollment fee is $26.40 a year.34PRC: Mail Classification Schedule through July 12, 2026 (docx, converted to HTML with mammoth)“(Revisions Through July 12, 2026) … | Online Enrollment (Commercial, ~~and~~ Residential, and Local) | 26.40 | … Customers must pay the Online Enrollment fee annually.”USPS original The mail ships in containers that pay Priority Mail Express or Priority Mail postage, or in flat rate tray boxes where USPS has them.34PRC: Mail Classification Schedule through July 12, 2026 (docx, converted to HTML with mammoth)“Containers are used based on volumes and are charged the appropriate Priority Mail Express or Priority Mail postage. … Flat rate tray boxes may be used, when available.”USPS original

An ancillary service endorsement is printed on the piece, and USPS reads it when the piece is undeliverable as addressed.16Guide to Move Updatepage 29“Ancillary Service Endorsements are printed on a mailpiece and recognized by the Postal Service when processing UAA mail.”USPS original The endorsements are the same for every mail class, but the treatment and cost differ by class.26Ancillary Services for Parcel Select and Parcel Select Lightweight FAQsPDF page 1“The endorsements are the same for all classes of mail, but the treatment and cost differ by class of mail.”USPS original Using one means the mailer agrees to pay any fees the services add.16Guide to Move Updatepage 29“The use of an Ancillary Service Endorsement represents the mailers’ acknowledgement of an agreement to pay any additional fees associated with these additional services.”USPS original

With ACS, the endorsements have disposition options that manual address correction lacks.38Guide to Move Updatepage 40“ACS Ancillary Service Endorsements have additional mail disposition options that are not available with manual address corrections.”USPS original Each option has its own Service Type ID, a code the mailer puts in the Intelligent Mail barcode.38Guide to Move Updatepage 40“Each of the endorsements and options have Service Type IDs assigned to them that must be used in the IMb when these options are desired.”USPS original

Electronic Service Requested only points to the actual service, which the barcode or the mailer's ACS profile names.39Guide to Move Updatepage 52“Electronic Service Requested must be used in conjunction with ACS/OneCode ACS/Full-Service ACS, but Electronic Service Requested just acts as a pointer to another actual service, such as Address Service Requested or Change Service Requested which exists in the Intelligent Mail barcode or in the mailer’s ACS profile.”USPS original When the barcode's Service Type ID and the printed endorsement disagree, the printed endorsement takes precedence.40Guide to Move Updatepage 30“If a conflict exists between the request represented by the Service Type ID in the IMb and the printed ancillary service endorsement, the printed endorsement will take precedence.”USPS original

Without ACS, the notice is a printed form or the returned piece.17A Guide to Full Servicepage 14“When an ASE is used without an ACS, either a hard copy address correction (PS Form 3547 or 3579) or the return of the piece fulfills the mailer's request.”USPS original PS Form 3547 shows an image of the piece with the new address or the reason it was not delivered.17A Guide to Full Servicepage 14“PS Form 3547 provides an image of the First-Class, Standard, or package services mailpiece with either the recipient's new address or the reason the piece couldn’t be delivered.”USPS original For Periodicals, PS Form 3579 gives the address and the correction or reason, and goes to the publisher named in the postage statement.17A Guide to Full Servicepage 14“PS Form 3579 for periodicals consists of the mailpiece address and the address correction or reason for nondelivery. … It is mailed to the publisher identified in the postage statement.”USPS original Manual notices are often the most costly and least effective way to keep a list current.3Guide to Move Updatepage 28“However, because stand-alone Ancillary Service Endorsements require manual operations, they are often the most costly and least effective way to maintain address lists for customer change-of-address.”USPS original

ACS reports two situations: the addressee filed a change of address, or the piece is undeliverable for another reason.10Mailer's Technical Advisory Committee - Best Practices for ACS™page 39“ACS provides electronic notification for two different types of Undeliverable-as-Addressed (UAA) mail situations; either there is a COA on file, or the mail is determined to be UAA for a reason other than a move (i.e. Attempted Not Known, No Such Number, Unable To Forward/Forwarding Time Expired).”USPS original Notices of the second kind, called Nixies, come from what the delivery employee knows about the addressee and the address.43Mailer's Technical Advisory Committee - Best Practices for ACS™page 8“This is because ACS Nixies result from the delivery employee knowledge regarding the addressee and the address.”USPS original A change-of-address notice gives a foreign new address when USPS knows it.44Appendix B: ACS™ Frequently Asked Questionspage 5“Yes, if known.”USPS original45Mailer's Technical Advisory Committee - Best Practices for ACS™page 28“ACS can provide the foreign address, but NCOALink cannot because NCOALink provides only delivery point valid (DPV) addresses.”USPS original

USPS charges no fee to sign up for ACS, but charges for each record.46Appendix B: ACS™ Frequently Asked Questionspage 4“There are no fees for signing up for ACS; however, there are fees for each record provided.”USPS original Electronic notices cost much less than manual ones.13Guide to Move Updatepage 4“Electronic and automated address correction fees are significantly lower than the fees charged for manual (hard-copy) address correction notices.”USPS original Full-Service ACS is free for qualifying Full-Service mail, though forwarding fees still apply.47Appendix C: ACS™ Product Code Information and Detailspage 4“In addition to full-service postage discounts and benefits, FS ACS is provided at no charge for qualifying full-service mail pieces.”USPS original48Guide to Move Updatepage 36“Full-Service ACS is provided at no charge, but forwarding fees will be applied.”USPS original When mail properly prepared for ACS gets a manual notice instead, the mailer is entitled to pay the electronic fee.49Mailer's Technical Advisory Committee - Best Practices for ACS™page 16“Manual COA and Nixie notices provided on mail that was properly prepared to generate ACS, but a PS Form 3547 or 3579 was generated instead, are entitled to pay the Electronic address correction fees.”USPS original The mailer must ask its local Post Office for a refund of the difference.49Mailer's Technical Advisory Committee - Best Practices for ACS™page 16“A refund for the difference in fees charged must be requested at your local Post Office.”USPS original

SingleSource ACS invoices come from the National Customer Support Center in Memphis.50Appendix B: ACS™ Frequently Asked Questionspage 9“SingleSource ACS invoices come from the NCSC in Memphis, TN instead of going through Eagan, MN and San Mateo, CA.”USPS original51SingleSource ACS™ Technical Guide page 6“The United States Postal Service® provides support for SingleSource ACS through the National Customer Support Center (NCSC) in Memphis TN.”USPS original Each must be paid, with a copy of its remittance slip, within 30 days of the invoice date.52SingleSource ACS™ Technical Guide page 10“Payment must be submitted with a copy of the invoice remittance slip within 30 days of the invoice date.”USPS original As of October 18, 2019, they could be paid by credit card or ACH credit, an overnight bank-to-bank transfer.52SingleSource ACS™ Technical Guide page 10“October 18, 2019 v 1.12 … Credit Card and ACH Credit payment options available to NCSC Accounting customers please contact the NCSC Accounts Receivable Department at 901-681-4658 for information.”USPS original53Enterprise Payment System (EPS) Deposit Instructionspage 1“ACH Credit is an overnight method of moving funds from one bank to another.”USPS original The center's Accounts Receivable Department, at 901-681-4658, gave the details.52SingleSource ACS™ Technical Guide page 10“Credit Card and ACH Credit payment options available to NCSC Accounting customers please contact the NCSC Accounts Receivable Department at 901-681-4658 for information.”USPS original Customers of the Electronic Payment System could instead email acs@usps.gov to have their ACS account set up for it.52SingleSource ACS™ Technical Guide page 10“October 18, 2019 v 1.12 … Electronic Payment System (EPS) customers can email acs@usps.gov and request your ACS account to be setup for EPS.”USPS original

USPS licenses neither the Intelligent Mail barcode nor ACS, and it recommends no service provider.44Appendix B: ACS™ Frequently Asked Questionspage 5“The Postal Service does not license the Intelligent Mail® barcode or the ACS product. … There may be service providers that may be able to perform this function for you; however, the USPS cannot recommend any particular company.”USPS original USPS recommends testing the barcode before mailing by sending at least 20 sample pieces for review.54OneCode ACS® Technical Guide page 38“The following procedures are voluntary and are not required for activation; however the Postal Service highly recommends that your Intelligent Mail barcode is tested prior to mailing. … Once a mailpiece has been finalized, create a minimum of 20 sample mailpieces that contain the Intelligent Mail Barcode.”USPS original The samples should carry different names and addresses, not one piece printed again and again.44Appendix B: ACS™ Frequently Asked Questionspage 5“The samples should reflect different names and addresses. Printing the same piece repeatedly does not reflect a real world scenario.”USPS original For Full-Service ACS, each piece's barcode must be unique for 45 days from the postage statement mailing date.55A Guide to Full Servicepage 2“Ensure all containers, trays, and pieces have an Intelligent Mail Barcode that is unique for 45 days from the postage statement mailing date.”USPS original56Appendix B: ACS™ Frequently Asked Questionspage 8“The 45-day window starts on the day the piece was mailed in a Full Service mailing.”USPS original

OneCode, Traditional and SingleSource ACS notices arrive through Electronic Product Fulfillment, the secure USPS website that also posts USPS address products.44Appendix B: ACS™ Frequently Asked Questionspage 5“OneCode, Traditional & SingleSource ACS customers use the EPF website.”USPS original57Mailer's Technical Advisory Committee - Best Practices for ACS™page 43“a secure web-based application managed by the National Customer Support Center in Memphis TN that is used to post and receive Address Management and Address Information System products, including ACS fulfillment files.”USPS original Full-Service ACS notices arrive as COA and Nixie reports in the Business Customer Gateway.58Mailer's Technical Advisory Committee - Best Practices for ACS™page 19“Full-Service ACS is made available through the ACS COA and Nixie Reports in the Business Customer Gateway.”USPS original SingleSource ACS is open to all mailers who want every notice in one file from one source.51SingleSource ACS™ Technical Guide page 6“While intended and designed primarily for Full Service qualified mailers, SingleSource ACS is available to ALL mailers that desire to receive all of their ACS notices in a single file format and from a single fulfillment source.”USPS original

An existing Traditional ACS or OneCode ACS account can become a SingleSource account.59SingleSource ACS™ Technical Guide page 13“An existing Traditional ACS or OneCode ACS account may be changed to a SingleSource account or you may request a new SingleSource account.”USPS original The mailer completes the ACS Enrollment Form with its existing ACS account number, shown on its ACS invoices as the MEM number.59SingleSource ACS™ Technical Guide page 13“To change an existing ACS account to a SingleSource account, complete the ACS Enrollment form and include your existing ACS account number in the fields provided. … If you do not know your existing ACS Account number, you can find it on the current ACS Invoices, identified as the “MEM” number.”USPS original A Traditional ACS account needs a Mailer ID, the 6- or 9-digit number that identifies a mailer, added before it can change.59SingleSource ACS™ Technical Guide page 13“Existing Traditional ACS accounts that are changed to a SingleSource account must have a MID added to the account before it can be changed.”USPS original60Publication 199: Intelligent Mail Package Barcode (IMpb) Implementation Guide for Confirmation Services and Electronic Payment Systemspage 474“MID is a unique 6- or 9-digit number that identifies the mailer or the mailer’s client.”USPS original A mailer that already uses Electronic Product Fulfillment needs no new access request on PS Form 5116 unless it wants another login.56Appendix B: ACS™ Frequently Asked Questionspage 8“If you are already an OneCode or Traditional ACS customer, you are a current EPF user and you will not need to submit an additional Web Access Request Form (PS 5116), unless an additional EPF login is desired.”USPS original

First-Class Mail postage covers basic forwarding and return, but not address correction fees.67Ancillary Service Endorsement Fact SheetPDF page 1“First-Class Mail postage covers basic forwarding and return service but does not include Address Correction Service fees.”USPS original USPS Marketing Mail postage covers neither forwarding nor return.67Ancillary Service Endorsement Fact SheetPDF page 1“USPS Marketing Mail postage does not cover forwarding and return service.”USPS original The weighted fee applies when USPS Marketing Mail or nonprofit mail carries an endorsement that asks for forwarding.68Mailer's Technical Advisory Committee - Best Practices for ACS™page 17“The weighted fee is applied when Marketing Mail and Nonprofit mail is endorsed with an ancillary service that includes a request for forwarding.”USPS original A Marketing Mail piece endorsed Return Service Requested pays a single-piece price for its weight and shape when it comes back.7DMM 507: Mailer Services“The mailer of a returned piece endorsed “Return Service Requested” is charged the applicable single-piece First-Class Mail or USPS Ground Advantage – Retail price for the weight and shape of the piece, and the nonmachinable surcharge if applicable.”USPS original

Forwarded Package Services parcels arrive postage due at the new address.9Traditional ACS™ with Shipper Paid Services Technical Guidepage 7“Package Services parcels and Bound Printed Mail flats that must be forwarded will arrive as “Postage Due” at the new address.”USPS original If the addressee refuses to pay, the parcel goes back and the mailer pays both forwarding and return postage.9Traditional ACS™ with Shipper Paid Services Technical Guidepage 7“If the addressee refuses the piece to avoid paying the forwarding postage, the parcel is returned to the mailer, and both the forwarding and return postage is charged.”USPS original Shipper Paid Services lets the shipper pay forwarding postage through its ACS account, so a refusal is less likely.9Traditional ACS™ with Shipper Paid Services Technical Guidepage 7“Shipper Paid Service provides an option for the shipper to pay the forwarding postage via the ACS account, minimizing the chance that the parcel will be refused.”USPS original Its Shipper Paid Return option lets the shipper pay return postage for undeliverable parcels through the same account.69Intelligent Mail® Package Barcode (IMpb) ACS™ Technical Guidepage 9“Shipper Paid Forwarding / Return (SPF/R) service is an IMpb ACS fulfillment option that allows parcel shippers to receive an electronic address correction notice and pay forwarding or return postage for their undeliverable parcels via their ACS account. … They may also pay for any return postage via Shipper Paid Return services if desired.”USPS original

For IMpb ACS, USPS takes a forwarded or returned parcel's weight and mail class from the detail record of its Shipping Services File, version 1.7 or higher.70Intelligent Mail® Package Barcode (IMpb) ACS™ Technical Guidepage 12“The weight and mail class of the parcel is determined by the detail record of the Shipping Services File (SSF - version 1.7 or higher). … The weight and mail class of the parcel provided in the detail record of the Shipping Services File (SSF) version 1.7 or higher).”USPS original That file holds the package's manifest and payment information.60Publication 199: Intelligent Mail Package Barcode (IMpb) Implementation Guide for Confirmation Services and Electronic Payment Systemspage 474“The electronic file containing all manifest and payment information.”USPS original A package with scan events but no manifest is unmanifested.71Publication 199: Intelligent Mail Package Barcode (IMpb) Implementation Guide for Confirmation Services and Electronic Payment Systemspage 476“Packages for which the USPS has scan events and no associated manifest are considered unmanifested.”USPS original As of January 6, 2026, USPS Ship flags an undeliverable package returned past 120 days as unmanifested.72USPS Ship Frequently Asked Questionspage 1“Updated January 6, 2026”USPS original73USPS Ship Frequently Asked Questionspage 6“We are working on putting in specific requirements to detect those instances and turn off the unmanifested fees, because right now, when these packages are returned past 120 days they are flagged as unmanifested.”USPS original As of that date, USPS was working on requirements to detect such returns and turn off the fees for unmanifested packages.72USPS Ship Frequently Asked Questionspage 1“Updated January 6, 2026”USPS original73USPS Ship Frequently Asked Questionspage 6“We are working on putting in specific requirements to detect those instances and turn off the unmanifested fees, because right now, when these packages are returned past 120 days they are flagged as unmanifested.”USPS original

Bulk Parcel Return Service, one of USPS's return services, brings large quantities of undeliverable USPS Marketing Mail machinable parcels back to designated postal facilities.74DMM 505: Return Services (July 2026)“Bulk parcel return service (BPRS) allows mailers of large quantities of USPS Marketing Mail machinable parcels that are undeliverable-as-addressed or un-opened and refused by addressees to be returned to designated Postal Service facilities.”USPS original The mailer pays only a per-piece fee for each parcel returned, not postage, and the service's permit carries no annual fee.74DMM 505: Return Services (July 2026)“Each piece returned through BPRS is charged only the per piece fee, not postage, regardless of weight. … A BPRS permit is required to participate in BPRS; no annual fee is required to obtain a BPRS permit.”USPS original

• An ancillary service endorsement needs a return address on the face of the piece.78PostalPro: Ancillary Service Endorsements“A return address is required on the face of the mailpiece when using ancillary service endorsements.”USPS original
• USPS does not accept mail that bears invalid or conflicting endorsements.7DMM 507: Mailer Services“Material bearing invalid or conflicting ancillary service endorsements will not be accepted for mailing.”USPS original
• Printing Electronic Service Requested on mail that does not ask for ACS adds work, and the mailer will likely pay the cost.28Mailer's Technical Advisory Committee - Best Practices for ACS™page 9“If Electronic Service Requested is printed on mail that does not request ACS, it will cause unnecessary and costly additional workload for the Postal Service, and you will likely have to pay any postage or fees that are charged as a result of its improper use.”USPS original
• ACS is not guaranteed, so some manual notices still arrive.79Traditional ACS™ Technical Guidepage 10“ACS is not a guaranteed service. Manual notices may still be received, although reduced in volume.”USPS original
• When an addressee refuses a postage-due parcel, the mailer pays both forwarding and return postage, which Shipper Paid Services makes less likely.9Traditional ACS™ with Shipper Paid Services Technical Guidepage 7“If the addressee refuses the piece to avoid paying the forwarding postage, the parcel is returned to the mailer, and both the forwarding and return postage is charged. … Shipper Paid Service provides an option for the shipper to pay the forwarding postage via the ACS account, minimizing the chance that the parcel will be refused.”USPS original
• An unendorsed Parcel Select package that comes back pays return postage at the USPS Ground Advantage Commercial price plus the additional service fee.7DMM 507: Mailer Services“Same treatment as “Forwarding Service Requested.” … Piece returned with reason for nondelivery attached; return postage charged at the applicable Package Services single-piece price or the USPS Ground Advantage – Commercial price plus the additional service fee.”USPS original
• A parcel with a registered Mailer ID but no printed endorsement gets no IMpb ACS notice.80Intelligent Mail® Package Barcode (IMpb) ACS™ Technical Guidepage 16“If the registered MID is used in the IMpb on a parcel of any mail class that has no printed ancillary endorsement, IMpb ACS will not be provided.”USPS original
• Pieces that institutions such as hospitals and universities return as undeliverable produce no ACS records.81Traditional ACS™ Technical Guidepage 13“COA records from colleges and universities, individuals within a business, or other single-point deliveries including, but not limited to, commercial mail receiving agencies (CMRA), prisons, hospitals, nursing homes, campus dormitories, and sorority or fraternity houses are not accepted or processed by the USPS. … Pieces returned as undeliverable by these institutions are not eligible to produce ACS records.”USPS original
• Full-Service ACS notices that cannot be matched to the mailing's electronic documentation are charged in the next billing cycle.50Appendix B: ACS™ Frequently Asked Questionspage 9“Mailpieces with a Full Service STID that cannot be matched to an eDoc are considered “Unassociated” and are not provided in the Full Service COA and Nixie reports through the Business Customer Gateway. … The Unassociated IMb is reported to the mailer and charges are applied for the record in the next available billing cycle.”USPS original
• USPS gives no refund for duplicate OneCode ACS notices from several pieces mailed to the same addressee.82OneCode ACS® Technical Guide page 14“Refunds for duplicate ACS notices will not be provided for multiple ACS notices generated from multiple mail pieces that request ACS and are mailed to the same addressee.”USPS original