--- title: "What is mailability?" description: "Mailability is whether a contact has a complete, deliverable, USPS-verified postal address, the direct mail equivalent of a valid email address." canonical: https://trysincerely.com/glossary/mailability last_updated: 2026-08-18 --- # What is mailability? > Mailability is whether a contact has a complete, deliverable, USPS-verified postal address, the direct mail equivalent of a valid email address. Source: https://trysincerely.com/glossary/mailability Mailability is whether you can actually send a physical piece to a contact. A record is mailable when it has a complete postal address that verifies as deliverable and is not on a suppression list. It is the direct mail equivalent of a valid email address, and in B2B it is rarer than you expect. ## Why it matters CRMs are built for email, so postal fields rot quietly. A typical B2B database is full of records with no address at all, an old office, or a half-filled street line. None of that blocks an email campaign, so nobody notices until mail comes back. Every unmailable record you print anyway costs real money. A letter runs one to two dollars in print and postage, and an undeliverable one buys you nothing but a [return to sender](https://trysincerely.com/glossary/return-to-sender). Unlike a bounced email, you cannot re-send it for free. Checking mailability up front turns a guess into a number. The pipeline is usually [address resolution](https://trysincerely.com/glossary/address-resolution) to fill gaps, then [CASS](https://trysincerely.com/glossary/cass) verification against USPS data, then a check against your [suppression list](https://trysincerely.com/glossary/suppression-list). What survives is your mailable audience, and that count, not your CRM count, is what a campaign can reach. Sincerely runs this audit on the free plan before you pay anything: connect Salesforce, HubSpot, or a CSV and see how many contacts are mailable today. Address verification is included on every plan, and nothing prints to an unverified address. ## Example You sync 1,000 target accounts. 240 have no postal address, 90 fail verification, and 12 are suppressed. Your mailable audience is 658. Knowing that before launch beats discovering it as returned mail three weeks after. Mailability is the first question of any direct mail campaign: not what you will say, but who you can physically reach. --- 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.