email-mcp

MCP server that turns the existing email_bridge.py workflow into one outbound email tool with automatic single-thread mapping.

Tool

• send

  • Sends an email in the mapped Gmail thread.

  • First call creates the thread.

  • Later calls keep replying in that same thread.

Related MCP server: Gmail Plugin MCP Server

Automatic Thread Mapping

Mapping key selection order:

1. explicit context_id argument

2. CODEX_THREAD_ID env var

3. CODEX_SESSION_ID env var

4. fallback: process-scoped key (proc-<pid>-<random>)

Behavior:

• One mapping key -> one Gmail thread.

• Mapping is stored in ~/.codex/email-bridge/mcp-state/thread-map.json.

• For non-Codex clients, pass context_id in tool calls if you want separate Gmail threads per chat/session.

• Optional override: set EMAIL_MCP_PROCESS_SESSION_KEY to force a fixed fallback key.

Prerequisites

This server includes a local bridge script at bridge/email_bridge.py (used as fallback when direct SMTP mode is unavailable).

Configure the same mailbox env vars used by that script:

• CODEX_EMAIL_ADDRESS

• CODEX_EMAIL_PASSWORD

• CODEX_EMAIL_TO (or pass to in tool calls)

• optional SMTP/IMAP host/port vars from the email-bridge docs

Install

cd email-mcp
npm install

Add To Your App (MCP)

This is a local stdio MCP server.

• command: node

• args: ["/absolute/path/to/email-mcp/index.js"]

• env: mailbox credentials + optional tuning flags

Recommended env vars:

• CODEX_EMAIL_ADDRESS

• CODEX_EMAIL_PASSWORD

• CODEX_EMAIL_TO

• EMAIL_MCP_PREWARM=true

• EMAIL_MCP_BRIDGE_SCRIPT=/absolute/path/to/email-mcp/bridge/email_bridge.py

• EMAIL_MCP_PYTHON=python3

Codex (~/.codex/config.toml)

Add this in ~/.codex/config.toml:

[mcp_servers.email]
command = "node"
args = ["/absolute/path/to/email-mcp/index.js"]
tool_timeout_sec = 3600

[mcp_servers.email.env]
CODEX_EMAIL_ADDRESS = "your_email@gmail.com"
CODEX_EMAIL_PASSWORD = "your_app_password"
CODEX_EMAIL_TO = "recipient@example.com"
EMAIL_MCP_PREWARM = "true"
EMAIL_MCP_BRIDGE_SCRIPT = "/absolute/path/to/email-mcp/bridge/email_bridge.py"
EMAIL_MCP_PYTHON = "python3"

tool_timeout_sec can stay high if you want one shared default, but this send-only server does not need long blocking timeouts.

Cursor (~/.cursor/mcp.json or project .cursor/mcp.json)

Add:

{
  "mcpServers": {
    "email-mcp": {
      "command": "node",
      "args": ["/absolute/path/to/email-mcp/index.js"],
      "env": {
        "CODEX_EMAIL_ADDRESS": "your_email@gmail.com",
        "CODEX_EMAIL_PASSWORD": "your_app_password",
        "CODEX_EMAIL_TO": "recipient@example.com",
        "EMAIL_MCP_PREWARM": "true"
      }
    }
  }
}

Then restart Cursor.

Claude Code

Use MCP add with stdio:

claude mcp add --transport stdio \
  --env CODEX_EMAIL_ADDRESS=your_email@gmail.com \
  --env CODEX_EMAIL_PASSWORD=your_app_password \
  --env CODEX_EMAIL_TO=recipient@example.com \
  --env EMAIL_MCP_PREWARM=true \
  email-mcp -- node /absolute/path/to/email-mcp/index.js

If your Claude client uses JSON mcpServers config instead, use the same block shown in the Cursor example.

Notes

• This MCP server only sends email.

• Incoming replies should be handled outside MCP by a watcher or intake flow, for example bridge/email_bridge.py watch --once, bridge/email_bridge.py wait, or your higher-level helper scripts.

• For stable Gmail threading, each mapped session uses one canonical subject base; later subject inputs are ignored for that session.

• send uses a pooled SMTP transport when SMTP env vars are present, which reduces repeated send overhead.

• Startup prewarm is enabled by default (EMAIL_MCP_PREWARM=true) and warms the SMTP path in the background.