Thunderbird MCP

# Thunderbird MCP [](LICENSE) [](https://www.thunderbird.net/) [](https://modelcontextprotocol.io/) > Inspired by [bb1/thunderbird-mcp](https://github.com/bb1/thunderbird-mcp). Rewritten from scratch with a bundled HTTP server, proper MIME decoding, and UTF-8 handling throughout. An MCP server that lets Claude Code read your email, search contacts, and draft replies in Thunderbird. ## How it works ``` Claude Code <--stdio--> mcp-bridge.cjs <--HTTP--> Thunderbird Extension ``` The Thunderbird extension runs a local HTTP server on port 8765. The Node.js bridge translates between MCP's stdio protocol and HTTP so Claude Code can talk to it. ## Setup **1. Install the extension** ```bash ./scripts/build.sh ./scripts/install.sh ``` Restart Thunderbird. **2. Configure Claude Code** Add to `~/.claude.json`: ```json { "mcpServers": { "thunderbird-mail": { "command": "node", "args": ["/path/to/thunderbird-mcp/mcp-bridge.cjs"] } } } ``` ## What you can do | Tool | What it does | |------|--------------| | `searchMessages` | Find emails by subject, sender, or recipient | | `getMessage` | Read full email content | | `searchContacts` | Look up contacts | | `listCalendars` | List your calendars | | `sendMail` | Open a compose window with pre-filled content | | `replyToMessage` | Open a reply with proper threading | Compose tools open a window for you to review before sending. Nothing gets sent automatically. ## Security The extension only listens on localhost, but any local process can access it while Thunderbird is running. Keep this in mind on shared machines. ## Troubleshooting **Extension not loading?** Check Tools → Add-ons and Themes. For errors: Tools → Developer Tools → Error Console. **Connection refused?** Make sure Thunderbird is running and the extension is enabled. **Can't find recent emails?** IMAP folders can be stale. Click on the folder in Thunderbird to sync, or right-click → Properties → Repair Folder. ## Development ```bash # Build the extension ./scripts/build.sh # Test the HTTP API directly curl -X POST http://localhost:8765 \ -H "Content-Type: application/json" \ -d '{"jsonrpc":"2.0","id":1,"method":"tools/list"}' # Test the bridge echo '{"jsonrpc":"2.0","id":1,"method":"tools/list"}' | node mcp-bridge.cjs ``` After changing extension code, you'll need to remove it from Thunderbird, restart, reinstall, and restart again. Thunderbird caches aggressively. ## Known issues - Replies don't include the quoted original message (Thunderbird limitation workaround) - IMAP folder databases can be stale until you click on them - Email bodies with weird control characters get sanitized to avoid breaking JSON ## Project structure ``` thunderbird-mcp/ ├── mcp-bridge.cjs # stdio-to-HTTP bridge ├── extension/ │ ├── manifest.json │ ├── background.js # Extension entry point │ ├── httpd.sys.mjs # Mozilla's HTTP server lib │ └── mcp_server/ │ ├── api.js # The actual MCP implementation │ └── schema.json └── scripts/ ├── build.sh └── install.sh ``` ## License MIT. The bundled `httpd.sys.mjs` is from Mozilla and licensed under MPL-2.0.