--- title: "What is mailability?" description: "Mailability checks whether a recipient can receive mail at a verified address and whether the sender has legal permission to mail them." canonical: https://trysincerely.com/glossary/mailability 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. # What is mailability? > Mailability checks whether a recipient can receive mail at a verified address and whether the sender has legal permission to mail them. Source: https://trysincerely.com/glossary/mailability Mailability is whether the intended person can receive a physical piece at the address on file and whether that person is eligible to be mailed. A complete street address is only one part of the answer. In B2B, the company may have moved, the contact may work elsewhere, or a durable suppression may prohibit the send. That makes mailability a contact-level verdict, not a synonym for address verification. ## Three questions that sound alike People use "mailable" for three different checks. They should stay separate. | Question | What it checks | What a pass does not prove | | --------------------------- | ------------------------------------------------------------------------------------------------ | --------------------------------------- | | Is the piece mailable? | The envelope or postcard meets postal rules for size, shape, weight, and preparation. | The destination exists. | | Is the address deliverable? | The address is complete and matches a recognized delivery point. | The intended person works there. | | Is the contact mailable? | The recipient is tied to that location, the address passes, and no suppression forbids the send. | That another piece should go out today. | A [frequency cap](https://trysincerely.com/guides/direct-mail-frequency-caps) can temporarily block a send even when the contact remains mailable. Suppression is different. It changes the contact's eligibility until someone with authority removes the durable decision. ## Verification is necessary, but it is not enough [Address resolution](https://trysincerely.com/glossary/address-resolution) finds the best current location for the person or account. Postal verification then checks the address itself. In the US, that usually includes CASS standardization and Delivery Point Validation. NCOA can catch a filed move. Those checks still cannot tell you that a vice president works at the headquarters listed on the company website. A headquarters can be a real delivery point and the wrong destination. Recipient fit needs evidence such as a current CRM record, company location page, business filing, or a recent role tied to that office. The last check is permission. A valid address does not override a [suppression list](https://trysincerely.com/glossary/suppression-list). It also does not restore somebody merely because a fresh CSV contains the person again. ## How to calculate a mailable audience Apply each test in order and keep the reason for every rejection. Do not collapse missing addresses, failed postal checks, and suppressions into one vague "bad data" bucket. They require different fixes. Suppose a campaign begins with 1,000 contacts: 1. Address resolution cannot find a credible business location for 240, leaving 760. 2. Postal verification rejects 90 of those records, leaving 670. 3. The suppression check removes 12 more, leaving a mailable audience of 658. That 658 is the reachable audience. The original 1,000 is still useful for diagnosing the list, but it is not an honest campaign denominator. ## What happens after the audit Mailability changes. People switch jobs, offices close, and opt-out requests arrive. Recheck close to dispatch rather than treating an import-time pass as permanent. If a piece comes back as [return to sender](https://trysincerely.com/glossary/return-to-sender), record the failure against the contact so another campaign does not repeat it. Sincerely resolves and verifies candidate addresses before anything prints. Uncertain matches go to review, suppressions apply across the workspace, and the final send path checks the verdict again. The useful question is not "Do we have an address?" It is "Can we responsibly put this person's name on an envelope bound for this address?" ## Related questions - [What is address resolution?](https://trysincerely.com/glossary/address-resolution): Address resolution finds the most likely current mailing location for a person or business before postal verification checks the address itself. - [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. - [What is a suppression list?](https://trysincerely.com/glossary/suppression-list): A suppression list is a durable do-not-contact record checked before every send. Learn what belongs on one, how exclusions differ, and why deletion fails. - [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. --- 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