Mail API for your product? Connect over OAuth.

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

Direct answer: Use USMail.ai MCP as the print-to-mail API behind your product or workflow: register one or more USMail.ai accounts, sign in with OAuth at app.usmail.ai/mcp, and your integration creates jobs, uploads documents and lists, requests proofs and reads status on the same production line as the app. The AI never suggests addresses; you supply every one.

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.

Agent files:

Start MailingSee how it works

Is USMail.ai MCP available now?

Yes. Live means you can use it on the app after you register; it does not mean an open server on the public internet. The public docs on this site describe it, a human account is required, and the MCP server for agents is live over OAuth at https://app.usmail.ai/mcp, on the same path as the app. The AI suggests setup, such as mail class, paper and color, and a human approves.

What does the USMail.ai MCP do?

An agent prepares print-to-mail jobs on the same production path as the app. It is not a second product, and it is not USPS. The agent can upload documents and lists, set options, request a proof and read status. It reads the addresses in the lists you supply and never suggests one. Approval follows the postage grant described below. The tools reference describes each capability in plain English.

Reference:

tools reference

Mixed Name and Company lists are valid. After ingest, read the digested rows, not only the column map.

How does postage grant work?

Physical mail can't be unsent once we produce it, and every job spends real postage. An agent can assemble a clean job and still be wrong about the recipients, the mail class or the date.

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. Until then, the job waits. An approved job can be unapproved until its mail date. Unapproving puts the money back on your meter, not back on your card. Agents don't run card deposits.

Do agent jobs use the same production path?

Yes. There is one backend. We print, insert, add postage and hand the pieces to USPS, with the same mail dates as the app, as described in How it works.

Certified Mail and Certificate of Mailing are available when you choose them on the job. 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. We check every address before mailing, and the AI never suggests an address; every address comes from you. USMail.ai is not USPS.

Production pages:

Is this a public mail API?

No. There is no open server for anonymous tool calls. 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. Do not invent endpoints, hostnames or install commands, and do not add a second connector.

What is the flow?

A human registers. The agent connects to the usmail server with OAuth. After it connects, it matches the skills version to initialize.serverInfo.version. The agent calls tools. Submit approves within your postage grant, or you Pay & Approve on the app. Then we produce the job and hand it to USPS. USMail.ai is an AI print-to-mail platform: You upload. You approve. We produce. The six steps, with failure notes, are on Getting started, and the rest of the reference lives in the USMail.ai docs.

What is not included?

MCP does not include an unauthenticated public server, unofficial install strings or a second connector, card deposits by agents, or a submit that spends postage when no postage grant is set.

What does production mail cost?

Production mail is billed per job. Letters starting at $1.15, postage included. For a one-page, single-sided, black-and-white First-Class letter.

You see the full price before you approve, you can pay per mailing or keep an optional meter balance, and there are no contracts, subscriptions or setup fees.

Pricing:

how pricing works

When does an approved letter 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.

What do people ask about USMail.ai?

What is the USMail.ai MCP?

A Model Context Protocol integration that lets AI agents prepare print-to-mail jobs on the same production path as the app, over OAuth at https://app.usmail.ai/mcp. A human sets postage grant, capped or uncapped.

How does billing work for MCP?

A human owns the account and its payment method. In the app, you pay per mailing or keep an optional meter balance. Agent approvals draw from your meter balance. Agents don't run card deposits.

Do agents use a different mail pipeline than people?

No. There is one production path for the app and MCP. We print, insert, add postage and hand the pieces to USPS.

Are mixed Name and Company lists valid?

Yes. Some rows have a person and a company, and some have only a name, where the name is the company. An empty company on those rows is correct. After ingest, read the digested rows.

Is this a public unauthenticated mail API?

No. MCP is OAuth at https://app.usmail.ai/mcp, tied to your account. Never put a password in a prompt, and don't invent hostnames or install commands.

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.

Start Mailing