Adding print-to-mail to your product? Start here.

By the USMail.ai team, more than 50 years of combined expertise in printing and mailing

Direct answer: Developers and companies use USMail.ai MCP as a print-to-mail API for their own products and workflows. You register one or more USMail.ai accounts, sign in with OAuth at app.usmail.ai/mcp, and build on the tools to create, upload, proof and approve mail jobs, with approved jobs paid from your meter balance.

These docs are for developers and companies that use USMail.ai MCP as the print-to-mail API in their own products and workflows. You register a USMail.ai account, or several, connect over OAuth, and then use the service like any other customer: your integration creates, uploads and proofs mail jobs and approves them once a person on the account turns on postage grant, and approved jobs are paid from the account's meter balance.

Documentation pages:

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What are these docs for?

These pages are the operator reference for USMail.ai MCP. You read them when you want print-to-mail and are ready to put the usmail server in an agent. They say what is live today and what we will not publish on this site. They are not a brochure, a public catalog of endpoints or a list of hostnames.

USMail.ai is an AI print-to-mail platform: You upload. You approve. We produce. The AI suggests setup, such as mail class, paper and color. It never suggests addresses; you supply every address. MCP does not create a second factory. Jobs from the app and jobs from an agent share the same printing, inserting, postage and handoff to USPS.

Two seats stay separate. You own the account and decide how much the agent may approve. The agent connects with OAuth and prepares the job. Submit stays inside the limit you set, and nobody puts a password in a prompt.

How do the docs differ from the product pages?

The /docs pages and the four MCP pages under them are operator docs: they explain how, not why. The MCP lander explains MCP to someone who has not connected yet, and How it works describes production for everyone.

Product pages:

Where should I start?

Start with Getting started: register, connect and set up payment. Agent rules live in AGENTS.md and skills live in skills.md, both linked from the MCP overview.

Agent files:

How does approval work when an agent prepares a job?

An agent can assemble the files, the options and a proof and still be wrong about the recipients, the mail class or the date. That's why a person keeps the final say on spending. A human turns on postage grant for the agent, capped or uncapped. With it on, the agent's submit approves a job within that limit, and the money comes from your meter balance. With it off, you review the job and Pay & Approve on the app.

When a job is approved, we print each letter, fold it, put it in an envelope, add postage and hand it to USPS. An approved job can be unapproved until its mail date. Unapproving puts the money back on your meter, not back on your card. Agents prepare jobs; they don't run card deposits.

How does an agent sign in?

The agent connects over OAuth at https://app.usmail.ai/mcp by signing in to your existing USMail.ai account (Connect / Authorize the usmail server). There is no separate key or token to copy, and you never put a password in a prompt. The only MCP host is https://app.usmail.ai/mcp. Do not invent hostnames, and do not add a second connector.

What will these pages not publish?

We don't publish install commands. The live tool list comes from the server after you connect, and the tools reference describes what the tools do in plain English. Never put a password in a prompt or in a public repo.

What does a mailing cost?

Letters starting at $1.15, postage included. For a one-page, single-sided, black-and-white First-Class letter.

Certified letters cost $1.15 plus the current USPS Certified Mail fee, and USPS tracking is included with every Certified letter. Certified is a mail class you choose before you approve, never an add-on. We don't offer paper Return Receipt yet. You see the full price before you approve, and you can pay per mailing or keep an optional balance on your meter. There are no contracts, subscriptions or setup fees.

When does an approved job go to USPS?

By default, letters you approve before 10 p.m. CT are handed to USPS the next business day. USPS delivery times vary. USPS handles delivery from there. We check every address before mailing, and the AI never suggests an address; every address comes from you. USMail.ai is not USPS.

What do people ask about USMail.ai?

Is MCP available?

Yes, on the app. MCP connects over OAuth at https://app.usmail.ai/mcp, the usmail server in the USMail.ai Cursor plugin. A human turns on postage grant for the agent, capped or uncapped, or approves each job on the app.

Do agents approve and spend postage?

Only within the postage grant a human sets. With it on, the agent's submit approves the job within that limit. With it off, you review and Pay & Approve on the app. Agents don't run card deposits.

How does an agent connect without a key?

It signs in over OAuth to your existing USMail.ai account at https://app.usmail.ai/mcp. There is no separate key to copy, and nobody puts a password in a prompt.

Does an agent job use a different production path?

No. Jobs from the app and jobs from an agent share printing, inserting, postage and the handoff to USPS, with the same mail dates.

Can an approved job be undone?

Yes. An approved job can be unapproved until its mail date. Unapproving puts the money back on your meter, not back on your card.

When does my letter go to USPS?

By default, letters you approve before 10 p.m. CT are handed to USPS the next business day (Monday to Friday). USPS delivery times vary. USPS handles delivery from there. There are no contracts, subscriptions or setup fees.

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