--- title: "What is dimensional mail?" description: "Dimensional mail is any mail piece with physical bulk, a box, tube, or lumpy envelope, priced as a parcel and used to force attention from hard-to-reach recipients." canonical: https://trysincerely.com/glossary/dimensional-mail last_updated: 2026-08-18 --- # What is dimensional mail? > Dimensional mail is any mail piece with physical bulk, a box, tube, or lumpy envelope, priced as a parcel and used to force attention from hard-to-reach recipients. Source: https://trysincerely.com/glossary/dimensional-mail Dimensional mail is any mail piece with physical bulk: a box, a tube, or an envelope with something lumpy inside. The name comes from postal pricing, where a piece that is not flat ships as a parcel instead of a letter. In B2B it usually means a gift or object sent to open a door at a high-value account. ## Why it matters Bulk gets opened. A box on a desk does not look like marketing, so it survives the gatekeeper and the recycling bin in a way a [self-mailer](https://trysincerely.com/glossary/self-mailer) or postcard cannot. That is the whole trade: you pay parcel postage plus the cost of the object, usually tens of dollars per piece all-in, to make one recipient stop and look. The economics only work at the top of the pyramid. Dimensional mail fits a ten-account executive play inside an [ABM](https://trysincerely.com/glossary/abm) program, not a thousand-piece prospecting run. At scale, the same budget mails far more letters and postcards, and [flat formats](https://trysincerely.com/formats) are easier to test, measure, and repeat. It also carries operational drag. Someone has to source the object, kit it, and ship it, which is why gifting platforms like Sendoso and Postal exist. Sincerely mails postcards, letters, and handwritten notes today, not boxes; if your play is dimensional, a gifting platform is the better tool, and our [gifting platform comparison](https://trysincerely.com/vs-gifting-platforms) covers when each makes sense. ## Example You target 15 accounts stuck in late-stage deals. Each economic buyer gets a book relevant to their initiative with a handwritten-style note. Call it $45 per piece shipped to make the arithmetic concrete; your real number depends on the object and the carrier. Total spend is under $700, and one revived deal pays for the program many times over. Dimensional mail is attention bought by the cubic inch: expensive per piece, so save it for the accounts that justify it. --- 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.