Integrating print-to-mail? Register, connect, build.

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

Direct answer: Get your integration mailing in six steps: register one or more USMail.ai accounts and set up payment, sign in with OAuth at app.usmail.ai/mcp, match the skills version, and call the tools. A person on each account sets postage grant or approves on the app, and nobody puts a password in a prompt.

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.

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What do I need before I start?

You need a USMail.ai account you control and a way to pay. In the app, you pay per mailing or keep an optional meter balance, and agent approvals draw from your meter balance. You don't need an install command from a blog. Use the USMail.ai Cursor plugin or Connect / Authorize the existing usmail server. Status and limits are on the MCP overview. If you're explaining MCP to someone who hasn't connected yet, send them to the MCP lander. 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, and a human approves.

What are the six steps?

Register. A human creates an account at app.usmail.ai. One account owns the app and MCP. Agents don't self-register, and jobs the agent prepares show on the app for review.
Set up payment. In the app, pay per mailing or keep an optional meter balance. Agent approvals draw from your meter balance, and agents don't run card deposits. See auth and billing.
Connect. 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.
After connecting, match the skills version to initialize.serverInfo.version. If it is older, re-read skills.md. Don't add a second connector.
Call tools. The agent calls tools on that server. Live names come from the server after you connect, and the tools reference describes them in plain English.
Postage grant. A human sets postage grant for the agent, capped or uncapped.

What can the agent do, and what needs a human?

The agent can create a job, upload documents and lists, set options and request a proof. It can cancel a draft that hasn't been approved. It doesn't print on its own, and it never suggests recipient addresses. We check every address before mailing, and the AI never suggests an address; every address comes from you. USMail.ai is not USPS.

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. Then we print, insert, add postage and hand the pieces to USPS, on the same path as an app job. An approved job can be unapproved until its mail date. Unapproving puts the money back on your meter, not back on your card. By default, letters you approve before 10 p.m. CT are handed to USPS the next business day. USPS delivery times vary.

Mail dates:

How it works

What does failure look like?

Sign-in fails: Connect / Authorize the existing usmail server again, and don't add a second connector.
The meter balance can't cover the job: connecting and the proof still work, but an agent approval is rejected. Production doesn't start until the job is paid, and there is no silent overdraft. Add to the meter balance, or a human can Pay & Approve on the app.
The server isn't authorized yet: authorize it, then retry.
Wrong seat: only a human sets postage grant or does Pay & Approve.
Invented connection: if a blog gives you a hostname or an install command, ignore it.

What does an example request look like?

"Upload notice.pdf and list.csv as First-Class. Send it Certified instead, and hold if the job is over my limit." That's an intent only; live tool names come from the MCP server's list. 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. See Certified Mail.

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

There are no contracts, subscriptions or setup fees.

Pricing:

how pricing works

What do people ask about USMail.ai?

What happens if connecting fails?

Connect / Authorize the existing usmail server at https://app.usmail.ai/mcp. Don't add a second connector, and never put a password in a prompt.

What happens if the meter balance can't cover the job?

Connecting, creating, uploading and the proof can still work. An agent approval is rejected, and production doesn't start until the job is paid. There is no silent overdraft. Add to the meter balance, or a human can Pay & Approve on the app.

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.

Do I need an install command or hostname?

No. MCP is OAuth at https://app.usmail.ai/mcp. Use the USMail.ai Cursor plugin or Connect / Authorize the existing usmail server.

Can the agent approve a job by itself?

Only within the postage grant a human sets. With it off, the job waits for a human to Pay & Approve on the app.

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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