How to send a real letter from ChatGPT

ChatGPT can draft the perfect letter, but until it has a way to reach a mailbox, you still have to print it, find a stamp and walk to the post office. Mailsnail is that way. It's a connector that gives ChatGPT tools to mail real USPS letters, and you set it up once by pasting a URL and signing in.

The source of truth for every app's setup is mailsnail.dev/setup. If a menu name here has drifted, the steps there are kept current.

Set it up

1. Turn on Developer mode. Custom connectors live behind Developer mode in ChatGPT's settings, in the connectors (or apps) section. Which plans include it changes, and on Business or Enterprise an admin may need to allow it.
2. Add a connector and paste this URL:

https://api.mailsnail.dev/mcp

3. Sign in. ChatGPT sends you to Mailsnail's sign-in page. Create an account or sign in and approve access. There's no API key to copy anywhere.

That's it. In a new chat, turn on the Mailsnail connector from the tools menu and it's ready.

Send your first letter

Try this:

Mail a letter to [your own address] that says "ChatGPT mailed this." Show me the proof and the price first.

Here's what happens:

1. verify_address checks that the address is deliverable. Free.
2. preview_letter renders the letter and returns a proof PDF and the exact price, still with nothing charged.
3. You look at the proof and say go.
4. send_letter mails it and returns a receipt token you can use later to check on it.

The first time, there's nothing on your account, so the send comes back with a link to a Mailsnail page where you pay for just that letter ($1.51 for a one-page letter). It's a one-time payment and your card isn't saved. Pay, tell ChatGPT to try again, and it mails. If you've already added funds to a Mailsnail balance from another app, ChatGPT draws on that balance instead.

What people mail from ChatGPT

• Thank-you notes and cards you meant to send and never did. Draft it together, approve it, done.
• Letters that need to be on paper: a complaint to a company, a records request, a dispute letter, a note to a landlord.
• Certified mail when you need proof it was sent, with a signed return receipt if you need proof it arrived. See how to send certified mail from an AI agent.

If you already have the letter as a PDF, give ChatGPT a link to it and it can mail that file instead of typing the text out.

Checking on a letter

Ask "what happened to the letter I sent yesterday?" and give it the receipt token. get_letter returns where the piece is. Changed your mind? cancel_letter stops a letter before the printer starts on it (usually about a day) and puts the full price back on your balance.

Related guides

• Send a letter from Claude, Cursor, or Codex: the same setup in other apps.
• How to send physical mail from an AI agent: the concepts, the tools, and what it costs.

claude mcp add -t http mailsnail https://api.mailsnail.dev/mcp

{
  "mcpServers": {
    "mailsnail": {
      "url": "https://api.mailsnail.dev/mcp"
    }
  }
}