mcp-mailer

A TypeScript MCP (Model Context Protocol) server for sending emails via SMTP.

Tools

send_email

Send an email via the configured SMTP server.

Parameter	Type	Required	Default	Description
to	string[]	✅	—	One or more recipient email addresses
subject	string	✅	—	Email subject line
body	string	✅	—	Email body (HTML or plain text)
html	boolean		true	Send body as HTML. Set false for plain text
from	string	✅	config default	Sender address override
cc	string[]		—	Optional CC recipients
reply_to	string		—	Optional Reply-To address

test_email

Sends a test email to the configured default sender address to verify SMTP connectivity. No parameters required.

Configuration

Option 1 — secrets.json (recommended)

Add an smtp block to ~/.openclaw/secrets.json:

{
  "smtp": {
    "host": "your-smtp-host",
    "port": 587,
    "user": "your-smtp-user",
    "pass": "your-smtp-password",
    "from": "sender@yourdomain.com"
  }
}

Option 2 — Environment variables

Environment variables take precedence over secrets.json:

Variable	Description	Default
SMTP_HOST	SMTP server hostname	—
SMTP_PORT	SMTP server port	587
SMTP_USER	SMTP authentication username	—
SMTP_PASSWORD	SMTP authentication password	—
EMAIL_FROM	Mail sender address	—
SMTP_SECURE	Use TLS on connect (true/false)	false
SMTP_REJECT_UNAUTHORIZED	Reject invalid TLS certs (false to disable)	true
SMTP_TIMEOUT	Connection timeout in ms	10000

Setup

npm install
npm run build

MCP Client Configuration

Add to your MCP client config (e.g. ~/.cursor/mcp.json or Claude Desktop config):

{
  "mcpServers": {
    "mcp-mailer": {
      "command": "node",
      "args": ["/path/to/mcp-mailer/dist/index.js"]
    }
  }
}

Security

• No telemetry or outbound connections beyond the configured SMTP server
• No credentials are hardcoded — always read from secrets.json or environment
• Secrets file is never logged or exposed via MCP tool responses