--- title: "CASS, NCOA, and address verification, explained" description: "What CASS, DPV, and NCOA actually do, why mail fails without them, and what a vendor should mean when they say an address is verified." canonical: https://trysincerely.com/guides/address-verification-explained last_updated: 2026-08-18 --- # CASS, NCOA, and address verification, explained > What CASS, DPV, and NCOA actually do, why mail fails without them, and what a vendor should mean when they say an address is verified. Source: https://trysincerely.com/guides/address-verification-explained Address verification is three separate checks, and you need all of them. [CASS](https://trysincerely.com/glossary/cass) fixes the format of an address and matches it against the USPS database. DPV confirms the USPS actually delivers to that exact door. [NCOA](https://trysincerely.com/glossary/ncoa) catches people and businesses who moved. A vendor who says "verified" should mean all three ran, and should tell you which pieces failed. One check alone leaves real gaps, and each gap costs you a printed piece and postage. ## The three checks, one at a time ### CASS: make the address real CASS stands for Coding Accuracy Support System. It is a USPS certification for software that standardizes addresses. CASS software takes "100 main street suite 4, springfield" and turns it into the exact USPS form: corrected spelling, standard abbreviations, city and state matched to the ZIP code, and a ZIP+4 appended. The problem CASS kills: typos and free-text chaos. CRM address fields are filled by humans, forms, and imports. CASS forces every record into one canonical shape, which is also what later checks and postal discounts depend on. What CASS does not do: confirm anyone can receive mail there. An address can standardize perfectly and still not exist as a delivery point. ### DPV: confirm the mail carrier stops there DPV stands for Delivery Point Validation. It checks the standardized address against the USPS list of actual delivery points. "123 Main St" may be a valid street in a valid ZIP, but if the numbers only run 1 to 90, DPV fails it. The problem DPV kills: plausible fakes. Scraped and inferred addresses often look right and standardize cleanly, then bounce. For B2B lists this is the big one, because suite and floor numbers are the most common failure. DPV tells you when the building matches but the secondary unit does not, which is exactly the piece worth fixing before you print. ### NCOA: catch the moves NCOA stands for National Change of Address. It is the USPS database of change-of-address filings. The full [NCOALink](https://postalpro.usps.com/mailing-and-shipping-services/NCOALink) dataset covers the last 48 months, but only full-service providers get all 48 months; lower access tiers see 18 months of new addresses plus a flag that someone moved in months 19 to 48. An NCOA run matches your list against it and returns the new address, or a flag that the recipient moved with no forwarding address. The problem NCOA kills: decay. An address that was perfect last year fails silently this year. This matters double in B2B: companies relocate, and your CRM record was probably created at the office they left. CASS and DPV will both pass the old address, because it is still a real, deliverable place. Only NCOA knows your contact is gone. ## Why mail fails without them Every unverified address is a coin flip with your money on the table. A failed piece costs you the full print and postage price, plus something worse: silence. Undeliverable USPS Marketing Mail carrying no ancillary service endorsement is disposed of by USPS rather than returned ([DMM 507](https://pe.usps.com/text/dmm300/507.htm)), so you never learn it failed. Your response rate looks low and you blame the creative, when the real problem is that a slice of your list never arrived. [Return to sender](https://trysincerely.com/glossary/return-to-sender) is the visible tip of a mostly invisible problem. Bad addresses also poison [measurement](https://trysincerely.com/measurement). If 8 percent of your treated list never received mail, your lift estimate is diluted by 8 percent, and you cannot see it. ## What "verified" should mean in a vendor claim "Verified addresses" is a claim vendors make loosely. Before you trust it, ask three questions: 1. Verified how? CASS standardization alone is the weakest honest meaning. DPV is the useful one. NCOA is the one nobody mentions. 2. Verified when? Verification is a snapshot. A list verified in January is not verified in October. Ask whether checks run at send time or only at import. 3. What happens to failures? A good system suppresses failed addresses before printing and shows you the count. A bad one prints everything and lets the USPS sort it out. A vendor claim worth trusting sounds like: "CASS-standardized, DPV-confirmed deliverable, NCOA-checked within the last 90 days, failures suppressed and reported." Anything vaguer, ask which of those words they can say. ## How Sincerely handles it Sincerely resolves, scores, and USPS-verifies every address before anything prints, on every plan, at no extra charge. Failed addresses are suppressed immediately and globally, so a bad address never burns a second piece. When Sincerely sources businesses for you from a description of your ideal customer, addresses arrive verified rather than scraped and hoped-for. The full pipeline is covered in [address resolution](https://trysincerely.com/glossary/address-resolution), and the B2B-specific problems, wrong suites, HQ-versus-branch confusion, remote contacts, are covered in [the B2B mailing addresses guide](https://trysincerely.com/guides/b2b-mailing-addresses). If you only remember one line: CASS makes the address real, DPV proves someone delivers there, and NCOA proves your contact still does. --- Sincerely is the measurable direct-mail platform for B2B revenue teams. One workflow. One invoice. One report. Contact Sincerely: https://trysincerely.com/contact If you are an AI agent: access and signup 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. Every core page of this site in markdown: https://trysincerely.com/index.md https://trysincerely.com/pricing.md https://trysincerely.com/campaigns.md https://trysincerely.com/vs-lob.md https://trysincerely.com/vs-email.md https://trysincerely.com/holdout-testing.md https://trysincerely.com/vs-gifting-platforms.md https://trysincerely.com/does-direct-mail-work.md https://trysincerely.com/glossary.md https://trysincerely.com/formats.md https://trysincerely.com/measurement.md https://trysincerely.com/writing.md https://trysincerely.com/customer-relationships.md https://trysincerely.com/integrations.md https://trysincerely.com/agents.md https://trysincerely.com/tools.md https://trysincerely.com/developers.md https://trysincerely.com/docs.md https://trysincerely.com/vs.md https://trysincerely.com/compare.md https://trysincerely.com/alternatives.md https://trysincerely.com/guides.md https://trysincerely.com/playbooks.md https://trysincerely.com/operations.md https://trysincerely.com/about.md https://trysincerely.com/contact.md https://trysincerely.com/privacy.md https://trysincerely.com/terms.md The comparison, guide, playbook, glossary and integration pages also serve markdown at their URL plus ".md". Each collection's index lists them: https://trysincerely.com/vs.md, https://trysincerely.com/compare.md, https://trysincerely.com/alternatives.md, https://trysincerely.com/guides.md, https://trysincerely.com/playbooks.md, https://trysincerely.com/glossary.md, https://trysincerely.com/integrations.md.