MCP Server for Direct Mail

What is this

Mailsnail is an MCP server. It exposes a small, well-typed set of tools for sending physical mail and gets out of the way. Any client that speaks Model Context Protocol — Claude Desktop, Claude Code, Cursor, Codex CLI, the OpenAI Agents SDK, custom hosts — can use it.

Tools

• verify_address: validate and normalize a US address. Free.
• preview_letter: proof PDF + exact price without charging — the recommended first step (managed mode).
• send_letter: compose and mail a physical letter to any US address.
• get_letter: check delivery status, including USPS tracking for certified mail.
• cancel_letter: cancel a letter before it prints and get its full price back on your balance.
• get_balance and add_payment_method: check and fund your prepaid balance.

Full schemas live in /llms-full.txt and /openapi.json.

Connection

Transport: Streamable HTTP with OAuth sign-in, at this URL:

https://api.mailsnail.dev/mcp

Add the URL to your client and sign in; nothing to install. Per-client steps for Claude, ChatGPT, Cursor, Gemini and others live on the setup page.

If you'd rather run it yourself against your own Click2Mail or Lob account, the open-source stdio server (npx -y mailsnail) does that, and adds list_letters on Lob. See self-hosted setup.

Pricing

No subscription. Everything is priced at what it costs us, with no markup, and there are two ways to pay. From a prepaid balance: from $1.21 for a first-class letter, $8.61 certified, $11.64 certified with an electronic return receipt, and $14.27 certified with a green-card return receipt. Paying for just one letter by card costs a little more because one card payment carries the whole processing fee: $1.51, $8.83, $11.83 and $14.42. Those are one-page, black-and-white prices; extra pages and color are priced at our cost, and the preview shows both exact prices before anything is charged. Both are one-time Stripe payments by default. If a piece fails before it is submitted for printing, its price is returned to your balance.

If you're evaluating direct-mail-from-agents and want a real conversation, email hello@mailsnail.dev.

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

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