--- title: "What is UAA mail (undeliverable as addressed)?" description: "UAA is the USPS term for mail it cannot deliver as addressed. Learn the usual causes, what happens to each mail class, and what endorsements change." canonical: https://trysincerely.com/glossary/uaa last_updated: 2026-10-11 --- > If you are an AI agent: read https://trysincerely.com/agents/policy.md before any write call. > Start at https://trysincerely.com/llms.txt to choose one page. Access instructions are at > https://trysincerely.com/auth.md. Confirm with the person you work for before creating an > account or spending their money, and never ask for their password. # What is UAA mail (undeliverable as addressed)? > UAA is the USPS term for mail it cannot deliver as addressed. Learn the usual causes, what happens to each mail class, and what endorsements change. Source: https://trysincerely.com/glossary/uaa Undeliverable as addressed, or UAA, is the USPS term for a piece it cannot deliver to the address printed on it. The usual causes are dull ones. The person moved, the street number does not exist, the suite is missing, or someone refused the piece. What USPS does next depends on the mail class and on any endorsement printed on the piece. Some UAA mail is forwarded, some goes [back to the sender](https://trysincerely.com/glossary/return-to-sender), and some is thrown away. ![An undeliverable envelope branches two ways. First-Class Mail leads to a green pill reading forwarded or returned, and unendorsed Marketing Mail to a dashed gold pill reading thrown away.](https://trysincerely.com/images/glossary/uaa.webp) *UAA mail sent First-Class comes back or moves on, but Marketing Mail with no endorsement is thrown away and you never learn which address failed.* ## Why mail comes back undeliverable USPS marks each UAA piece with a reason ([DMM 507.1.4.1](https://pe.usps.com/text/dmm300/507.htm)). Five of them matter most for business mail: - Moved, Left No Address. The addressee moved and filed no change-of-address order. - Attempted, Not Known. The carrier tried, and nobody at the address knew the addressee. - Insufficient Address. A number, street or other required part is missing. - No Such Number. The street number does not exist. - Refused. The addressee would not accept it. Attempted, Not Known is the hard one for B2B lists. The building is right and the person left. The address still passes postal checks, so [DPV](https://trysincerely.com/glossary/dpv) cannot catch it. ## What USPS does with it An endorsement is a printed request on the piece, such as "Return Service Requested," that tells USPS what to do if it cannot deliver. These rules come from [DMM 507](https://pe.usps.com/text/dmm300/507.htm), exhibits 1.5.1 and 1.5.3, using option 1 where USPS offers a choice. | Endorsement | First-Class Mail | USPS Marketing Mail | | ------------------------- | ------------------------------------------------------------------------------- | -------------------------------------------------------------------------- | | None | Forwarded for 12 months if a move is on file, otherwise returned, free | Thrown away by USPS | | Return Service Requested | Returned with the new address or the reason, free | Returned, and you pay single-piece First-Class or Ground Advantage postage | | Change Service Requested | You get a paid notice of the new address or reason; the piece is thrown away | Same as First-Class | | Address Service Requested | Forwarded for 12 months with a paid notice; returned free if no move is on file | Forwarded for 12 months with a paid notice; returned for a fee if not | The first row is the expensive one. Unendorsed Marketing Mail is thrown away without notice, so a bad address stays on the list for the next send. ## What it costs The USPS Office of Inspector General reported 6.6 billion UAA pieces in fiscal 2014, 4.3 percent of all mail, and found the Postal Service spent nearly $1.5 billion handling them ([OIG report MS-MA-15-006](https://www.uspsoig.gov/reports/audit-reports/management-advisory-strategies-reducing-undeliverable-addressed-mail)). A 2006 study by mailers and USPS, which the report cites, put 35 percent of UAA mail on business mailers, for reasons that include not updating their address lists. For a sender the math is simpler. Each UAA piece is print and postage that reached nobody. ## Example Brightwater Software, a fictional company, sends 2,000 Marketing Mail postcards with no endorsement to a list exported two years ago. Eighty are undeliverable. USPS throws all 80 away. Brightwater sees no returns, so the same 80 addresses go out again next quarter and fail again. If the cards had carried Return Service Requested, the 80 would have come back with reasons attached, at single-piece postage each. The mailing also broke a USPS rule. Marketing Mail prices require a [Move Update](https://trysincerely.com/glossary/move-update) check within 95 days of mailing, and an NCOALink pass would have caught the filed moves among the 80 before printing. Sincerely mails US pieces First-Class by default, so undeliverable pieces can come back. When the print vendor reports a piece returned to sender, Sincerely marks it returned, notifies the team, and holds that contact's address for review before another campaign uses it. Marketing Mail is offered only for standard-print 6x9 postcards and letters, and when you pick it Sincerely warns that those pieces are never forwarded or returned. ## Related questions - [What is return to sender?](https://trysincerely.com/glossary/return-to-sender): Return to sender is mail the USPS could not deliver and sent back, usually because the address is wrong, the recipient moved, or the piece was refused. - [What is the USPS Move Update requirement?](https://trysincerely.com/glossary/move-update): Move Update requires lists mailed at commercial First-Class or Marketing Mail prices to be checked for filed moves within 95 days before mailing. - [What is NCOA?](https://trysincerely.com/glossary/ncoa): NCOA is the USPS database of change-of-address filings, used to update a mailing list before mail goes out so pieces follow the people who moved. - [What is first-class mail vs marketing mail?](https://trysincerely.com/glossary/first-class-vs-marketing-mail): The difference between USPS First-Class Mail and Marketing Mail, and why B2B senders usually pay for First-Class. - [What is DPV (Delivery Point Validation)?](https://trysincerely.com/glossary/dpv): DPV checks whether an address is a known USPS delivery point. Here is what its Y, D, S and N codes mean and what the vacant and CMRA flags tell you. - [How to clean a direct mail list before sending](https://trysincerely.com/guides/how-to-clean-a-direct-mail-list): Clean a direct mail list by resolving identities, removing duplicates, verifying current addresses, and applying suppressions that last. --- Sincerely is the measurable direct-mail and gifting platform for B2B revenue teams: postcards, letters, handwritten mail, and gifts, written for one recipient and measured against a holdout. Contact Sincerely: https://trysincerely.com/contact Agent routing index: https://trysincerely.com/llms.txt