--- title: "CASS, NCOA, and address verification, explained" description: "CASS, DPV, and NCOA explained: what each does, why mail fails without them, and what verified actually means." canonical: https://trysincerely.com/guides/address-verification-explained last_updated: 2026-09-18 --- > 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. # CASS, NCOA, and address verification, explained > CASS, DPV, and NCOA explained: what each does, why mail fails without them, and what verified actually means. Source: https://trysincerely.com/guides/address-verification-explained For US mail, distinguish three things: CASS certifies address-matching software, DPV checks an address against postal delivery-point records, and NCOA checks filed changes of address. A formatted address alone is insufficient. None of these checks confirms that your intended recipient still works there. Canadian mail needs Canadian postal verification, not a USPS check. ## What each check tells you ### CASS: certified address processing [USPS CASS certification](https://postalpro.usps.com/certifications/cass) evaluates address-matching software. Certified processing standardizes addresses and assigns postal codes, and includes delivery-point checks. CASS is a certification of the software, not a delivery verdict for a particular contact. Software may correct a street abbreviation, match a city to a ZIP code, or flag missing information. Inspect the result for the individual address rather than treating a neatly formatted address as ready to mail. The [CASS glossary](https://trysincerely.com/glossary/cass) explains the distinction. ### DPV: a delivery-point record [Delivery Point Validation](https://postalpro.usps.com/address-quality/dpv) checks whether an address is represented in the USPS delivery-point file. Results can distinguish a confirmed building from an unconfirmed secondary unit. That distinction matters for offices with suites and shared mailrooms. A passing result does not identify the person behind the door or guarantee delivery of a future piece. Review incomplete suite information before printing. ### NCOA: filed moves [NCOALink](https://postalpro.usps.com/mailing-and-shipping-services/NCOALink) compares a mailing list with change-of-address filings. It can return a forwarding address or a move indication, depending on the match and available record. It only catches reported moves. A company may have left an office without filing a change, or your contact may have changed employers. A delivery-point check can still pass that old office. Neither result establishes the contact's current location. The [NCOA glossary](https://trysincerely.com/glossary/ncoa) covers this limit. ## Why address quality matters A failed piece costs print and postage without reaching the intended recipient. Undeliverable USPS Marketing Mail carrying no ancillary service endorsement is disposed of rather than returned under [DMM 507](https://pe.usps.com/text/dmm300/507.htm). Some failures therefore never appear as [return to sender](https://trysincerely.com/glossary/return-to-sender). Failed delivery can also dilute a campaign's [measured effect](https://trysincerely.com/measurement). Keep those accounts in the assigned treatment group for the primary analysis, and describe delivery problems separately. Removing failures after assignment would change the experiment. ## What to ask a verification vendor 1. Which country and postal records does the check cover? For US addresses, distinguish CASS-certified processing, DPV results, and any NCOA service. Do not assume that one implies all the others ran. 2. When was this address checked? Verification is a snapshot. Ask whether stale results are checked again before a send. 3. What happens to a failed or unavailable check? The system should retain the reason and keep unresolved addresses out of print until they pass review. 4. Does the check establish the intended recipient's connection to the address? Postal verification usually cannot answer that question. Review the source and location evidence separately. ## How Sincerely handles it Sincerely resolves addresses and checks mailability before printing. US addresses use USPS delivery-point checks; Canadian addresses use Canada Post verification. Address checks are included on every plan. An unavailable verification service leaves an address unresolved for later checking or review; it does not turn an unknown address into a passing one. Sourced addresses also need review of their provenance and fit for the intended contact. Failed addresses remain outside the mailable audience until resolved, while explicit suppression applies immediately across the workspace. This is not a claim that every address has been NCOA-checked or that postal verification confirms current occupancy. See [address resolution](https://trysincerely.com/glossary/address-resolution) for the source-to-review workflow and [B2B mailing addresses](https://trysincerely.com/guides/b2b-mailing-addresses) for headquarters, branch-office, and remote-contact decisions. ## Related questions - [What is CASS?](https://trysincerely.com/glossary/cass): CASS is the USPS certification for address-matching software. DPV checks delivery-point records, and neither one confirms who works at the address. - [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. - [How to get verified mailing addresses for B2B prospects](https://trysincerely.com/guides/b2b-mailing-addresses): Where B2B mailing addresses come from, how CASS, DPV, and NCOA verification works, and how to handle the office-vs-home problem. - [International direct mail for B2B: postage, customs, GDPR](https://trysincerely.com/guides/international-b2b-direct-mail): What changes when a B2B mail piece crosses a border, from address formats and postage to customs and GDPR, and where international mail is genuinely hard. --- 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. 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