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mcp server

mcp-server

Governed email for AI agents over MCP — sandbox inboxes, server-side policy gate, tamper-evident audit. Registry: com.mailbuttons/mcp-server

mailbuttons/mcp-servercommunitylistedunreviewed
Use tool

Set up

Runs on your computer. Pick your agent and operating system.

Before you start

  • Node.js 20 or newer
~/Library/Application Support/Claude/claude_desktop_config.json
{
  "mcpServers": {
    "mailbuttons-mcp-server": {
      "command": "npx",
      "args": [
        "-y",
        "@mailbuttons/mcp-server"
      ],
      "env": {
        "MAILBUTTONS_API_KEY": "<your MAILBUTTONS_API_KEY>"
      }
    }
  }
}

same format Cursor, GitHub Copilot CLI, Junie, JetBrains AI Assistant, Augment (Auggie CLI), Factory Droid, Kiro, Devin CLI +12

Values in angle brackets are placeholders. Restart Claude Desktop after editing its config.Claude Desktop docs

README

synced Oct 17, 2026

Mailbuttons MCP server

Governed email for AI agents, over the Model Context Protocol. Give an agent a scoped mailbox where the server enforces the guardrails, not the prompt: sandbox-by-default inboxes, a policy gate on every send, and a tamper-evident audit log. External sending and scope changes are human-approved, never granted by the agent itself.

Use it

Hosted (recommended) — a streamable-HTTP endpoint served by the platform:

https://mailbuttons.com/api/v1/mcp/rpc
Authorization: Bearer <your Mailbuttons MCP token>   # mb_sandbox_... (or mb_prod_...)

Local (stdio) — run the npm package and let your agent launch it:

{
  "mcpServers": {
    "mailbuttons": {
      "command": "npx",
      "args": ["-y", "@mailbuttons/mcp-server"],
      "env": { "MAILBUTTONS_API_KEY": "mb_sandbox_..." }
    }
  }
}

Get a scoped token from the dashboard or POST /api/v1/mcp/sandbox-inboxes. Sandbox tokens can never send externally until a human promotes them.

What the server enforces

  • Inbound — a per-mailbox sender policy, fail-closed: mail from strangers bounces by default, so nobody can prompt-inject your agent just by emailing it.
  • Outbound — a recipient blocklist the agent can read but not change; a blocked send returns a normal {"status":"blocked"} result, not an error.
  • Caps + audit — per-account send caps and a hash-chained audit log that records refusals too.
  • Escalation — sending externally or widening scope is propose-only; a named human approves. The agent cannot approve its own request.

Install as an agent skill

This repo ships a root SKILL.md, so any skills-aware agent can add it:

npx skills add mailbuttons/mcp-server

Docs

Mailbuttons is a trading name of Code Cutter Limited (UK, no. 08453060). MIT licensed.

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