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Mailly

Official registry Security

A real inbox for agents: read mail, draft replies you approve, wait for verification codes.

Source code Website Documentation

Install

Add this to your client's MCP configuration (Claude Desktop: claude_desktop_config.json; Cursor: .cursor/mcp.json; VS Code and others use the same "mcpServers" shape).

Remote (streamable-http)
Claude Code 
claude mcp add --transport http mailly 'https://mcp.mailly.site/mcp'
JSON configuration (Claude Desktop, Cursor, VS Code) 
{
    "mcpServers": {
        "mailly": {
            "type": "http",
            "url": "https://mcp.mailly.site/mcp"
        }
    }
}

Documentation

From the project's README on GitHub, refreshed weekly. Links open on GitHub.

Contents
  1. mailly-mcp
  2. Use the hosted server
  3. Run it yourself
  4. Develop
  5. License

mailly-mcp

The MCP server behind Mailly's connector, plus the Mailly plugin for Claude and Codex.

  • src/: the MCP server, a Cloudflare Worker. It offers typed tools for Mailly mail, drafts, sending, domains, contacts, templates, campaigns, workflows and webhooks. Every tool calls the Mailly REST API with the caller's Mailly API key, so authentication, billing and workspace isolation all stay in the API.
  • ui/: the MCP Apps UI (email and draft cards), bundled into ui:// resources. It is off unless MCP_APPS=1.
  • plugins/mailly: the plugin for Claude (claude.ai, Cowork and Claude Code) and Codex. It points at the hosted server and adds a skill for working with email safely.

Use the hosted server

Add https://mcp.mailly.site/mcp as a remote MCP server and sign in with your Mailly account (OAuth). In Claude Code you can install the plugin instead:

/plugin install mailly --marketplace superagents-lab/mailly-mcp

This server is an OAuth protected resource. Mailly's API (https://api.mailly.site/api/auth) is the authorization server: clients find it through /.well-known/oauth-protected-resource, sign the user in there, and send the access token here. The server passes the token, or an API key, unchanged to Mailly's REST API, which checks it and the scopes it carries. The tool list is narrowed to the same scopes (GET /me).

Run it yourself

npm install
npm run dev          # wrangler dev on http://localhost:8787/mcp

Call /mcp with Authorization: Bearer <your Mailly API key> (from https://mailly.site/app/developers). Without the MAILLY_API service binding it calls MAILLY_API_URL (default https://api.mailly.site) over the internet. To host your own copy, change the mcp.mailly.site route in wrangler.jsonc. OAuth sign-in only works at https://mcp.mailly.site/mcp, because Mailly issues tokens for that resource; elsewhere use an API key.

Develop

npm run typecheck
npm test             # builds dist/worker.js and runs it in Miniflare against a stub API

The Mailly server repository runs its OAuth and end-to-end tests against dist/worker.js from a sibling checkout of this repository.

server.json is the listing in the MCP Registry as site.mailly/mcp. The site.mailly namespace is proven by a DNS TXT record on mailly.site, so publish with mcp-publisher login dns --domain mailly.site --private-key <key> and mcp-publisher publish from a machine that holds the key. Bump version for each release.

License

MIT

Frequently asked questions

What is Mailly?

A real inbox for agents: read mail, draft replies you approve, wait for verification codes.

How do I install Mailly?

It runs as a remote server. In Claude Code: claude mcp add --transport http mailly 'https://mcp.mailly.site/mcp'. For other clients, paste the JSON configuration from this page into their MCP settings.

Does Mailly need an API key?

Its registry entry lists no required key or secret. Some features may still need an account with the service it connects to.

Is Mailly open source?

Yes. Its code is on GitHub under the MIT license.

Who maintains Mailly?

It is published by superagents-lab. AI.tn lists it but does not maintain or endorse it.

From the official MCP Registry. Listing is not an endorsement: review a server's code and permissions before giving it access to your data.