Reference

Getting started

Before you start

You need a USMail.ai account you control. You need a meter you can fund in the app. You need an agent environment you control. You do not need a hostname from this page. You do not need an add command from a blog. Do not invent hostnames or add commands. Connection details come with access on the app. Status and limits: MCP overview.

This walkthrough is the operator path. The lander is a different page. If you are explaining MCP to someone who has not connected yet, send /mcp. If you are connecting, stay here.

Steps

1. Register

   A human creates an account at app.usmail.ai. One account owns the portal and MCP.

2. Fund the meter

   Add prepaid balance in the app. Agents do not run card deposits.

3. Env credentials

   Put the account email and password in the agent environment. Never in the prompt.

4. Login

   Call the MCP login tool with those credentials. Ask it to return the session token.

5. Pass the token

   Pass that token on every later mail tool. It is short-lived.

6. Human approves

   Approve on the app to debit the meter and start production. See tools.

1. Register

Agents do not self-register. There is no MCP-only login. The email and password you create are the same credentials the agent will use from env. Jobs the agent prepares show on the app. You review them there. You do not get a second queue.

2. Fund the meter

The meter is the same one the portal spends. Approve on the app is the debit. Billing detail: Auth & billing.

3. Env credentials

Never in a gist. Never in a ticket you paste into chat. The password is a secret. Treat it like one. If the agent asks you to paste the password into the conversation, stop. Tell the agent to read env and call login. Account practices: Security.

4. Login

The token is short-lived. It is not a standalone API key. Standalone API keys are planned. Live tool names come from the MCP server after login. Tools reference describes capabilities in English.

5. Pass the token

Minutes, then it dies. Do not keep using a dead token. Do not put the password on later calls if the tool asks for the session token.

Keep the token in the agent's session memory or a local secret store. Do not commit it. Do not paste it into a public issue.

6. Human approves

The agent can create a job, upload documents and lists, set options, and request proof. It can cancel a draft. It does not print. You open the app. You review. You approve.

That debit starts production. We print, insert, apply postage, and deliver the pieces to USPS. Same path as a portal job. If a tool exposes a submit or persist step, it stores the job. It does not print. Cutoffs live on How it works.

What failure looks like

Auth fail. The login tool rejects the call, or later tools reject a missing or dead token. Check env. Log in again. Pass the new token. Do not retry the dead one.

Empty meter. Login and proof can still return. Production does not start. Insufficient balance blocks production. There is no silent overdraft. Fund in the app, then approve.

Missing env. The agent cannot complete login. Put credentials in the environment, then retry.

Wrong seat. If you wait for the agent to approve, the job stays a draft. Open the app. Review the proof. Confirm. That is the spend.

Invented connection. If a blog gives you a hostname or an add command, ignore it. Use what the app issues with access.

Example intent

Upload notice.pdf + list.csv as First-Class.
Add Certified. Hold if cost > $50. Do not approve until the meter covers it.

Intent only. Live tool names come from the MCP server list. The agent prepares. You approve on the app.

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

Certified is a mail option you add before you approve. Not for postcards. Never same-day. Certified Mail →

FAQ