An MCP server that provides tools for sending transactional emails and managing email templates via Mailtrap

Before using this MCP server, you need to:

1. Create a Mailtrap account
2. Verify your domain
3. Get your API token from Mailtrap API settings
4. Get your Account ID from Mailtrap account management

Required Environment Variables:

• MAILTRAP_API_TOKEN - Required for all functionality
• DEFAULT_FROM_EMAIL - Required for all email sending operations
• MAILTRAP_ACCOUNT_ID - Required for template management operations
• MAILTRAP_TEST_INBOX_ID - Only required for sandbox email functionality

For easy installation in hosts that support MCP Bundles, you can distribute an .mcpb bundle file.

# Build TypeScript and pack the MCPB bundle
npm run mcpb:pack

# Inspect bundle metadata
npm run mcpb:info

# Sign the bundle for distribution (optional)
npm run mcpb:sign

This creates mailtrap-mcp.mcpb using the repository manifest.json and built artifacts in dist/.

Add the following configuration:

{
  "mcpServers": {
    "mailtrap": {
      "command": "npx",
      "args": ["-y", "mcp-mailtrap"],
      "env": {
        "MAILTRAP_API_TOKEN": "your_mailtrap_api_token",
        "DEFAULT_FROM_EMAIL": "your_sender@example.com",
        "MAILTRAP_ACCOUNT_ID": "your_account_id",
        "MAILTRAP_TEST_INBOX_ID": "your_test_inbox_id"
      }
    }
  }
}

If you are using asdf for managing Node.js you must use absolute path to executable (example for Mac)

{
  "mcpServers": {
    "mailtrap": {
      "command": "/Users/<username>/.asdf/shims/npx",
      "args": ["-y", "mcp-mailtrap"],
      "env": {
        "PATH": "/Users/<username>/.asdf/shims:/usr/bin:/bin",
        "ASDF_DIR": "/opt/homebrew/opt/asdf/libexec",
        "ASDF_DATA_DIR": "/Users/<username>/.asdf",
        "ASDF_NODEJS_VERSION": "20.6.1",
        "MAILTRAP_API_TOKEN": "your_mailtrap_api_token",
        "DEFAULT_FROM_EMAIL": "your_sender@example.com",
        "MAILTRAP_ACCOUNT_ID": "your_account_id",
        "MAILTRAP_TEST_INBOX_ID": "your_test_inbox_id"
      }
    }
  }
}

Mac: ~/Library/Application Support/Claude/claude_desktop_config.json

Windows: %APPDATA%\Claude\claude_desktop_config.json

Mac: ~/.cursor/mcp.json

Windows: %USERPROFILE%\.cursor\mcp.json

Run in Command Palette: Preferences: Open User Settings (JSON)

Then, in the settings file, add the following configuration:

{
  "mcp": {
    "servers": {
      "mailtrap": {
        "command": "npx",
        "args": ["-y", "mcp-mailtrap"],
        "env": {
          "MAILTRAP_API_TOKEN": "your_mailtrap_api_token",
          "DEFAULT_FROM_EMAIL": "your_sender@example.com",
          "MAILTRAP_ACCOUNT_ID": "your_account_id",
          "MAILTRAP_TEST_INBOX_ID": "your_test_inbox_id"
        }
      }
    }
  }
}

Once configured, you can ask agent to send emails and manage templates, for example:

Email Operations:

• "Send an email to john.doe@example.com with the subject 'Meeting Tomorrow' and a friendly reminder about our upcoming meeting."
• "Email sarah@example.com about the project update, and CC the team at team@example.com"
• "Send a sandbox email to test@example.com with subject 'Test Template' to preview how our welcome email looks"

Template Operations:

• "List all email templates in my Mailtrap account"
• "Create a new email template called 'Welcome Email' with subject 'Welcome to our platform!'"
• "Update the template with ID 12345 to change the subject to 'Updated Welcome Message'"
• "Delete the template with ID 67890"

Sends a transactional email through Mailtrap.

Parameters:

• to (required): Email address(es) of the recipient(s) - can be a single email or array of emails
• subject (required): Email subject line
• from (optional): Email address of the sender, if not provided "DEFAULT_FROM_EMAIL" will be used
• text (optional): Email body text, required if "html" is empty
• html (optional): HTML version of the email body, required if "text" is empty
• cc (optional): Array of CC recipient email addresses
• bcc (optional): Array of BCC recipient email addresses
• category (required): Email category for tracking and analytics

Sends an email to your Mailtrap test inbox for development and testing purposes. This is perfect for testing email templates without sending emails to real recipients.

Parameters:

• to (required): Email address(es) of the recipient(s) - can be a single email or array of emails (will be delivered to your test inbox)
• subject (required): Email subject line
• from (optional): Email address of the sender, if not provided "DEFAULT_FROM_EMAIL" will be used
• text (optional): Email body text, required if "html" is empty
• html (optional): HTML version of the email body, required if "text" is empty
• cc (optional): Array of CC recipient email addresses
• bcc (optional): Array of BCC recipient email addresses
• category (optional): Email category for tracking

Creates a new email template in your Mailtrap account.

Parameters:

• name (required): Name of the template
• subject (required): Email subject line
• html (or text is required): HTML content of the template
• text (or html is required): Plain text version of the template
• category (optional): Template category (defaults to "General")

Lists all email templates in your Mailtrap account.

Parameters:

• No parameters required

Updates an existing email template.

Parameters:

• template_id (required): ID of the template to update
• name (optional): New name for the template
• subject (optional): New email subject line
• html (optional): New HTML content of the template
• text (optional): New plain text version of the template
• category (optional): New category for the template

Deletes an existing email template.

Parameters:

• template_id (required): ID of the template to delete

1. Clone the repository:

git clone https://github.com/railsware/mailtrap-mcp.git
cd mailtrap-mcp

1. Install dependencies:

npm install

Add the following configuration:

{
  "mcpServers": {
    "mailtrap": {
      "command": "node",
      "args": ["/path/to/mailtrap-mcp/dist/index.js"],
      "env": {
        "MAILTRAP_API_TOKEN": "your_mailtrap_api_token",
        "DEFAULT_FROM_EMAIL": "your_sender@example.com",
        "MAILTRAP_ACCOUNT_ID": "your_account_id",
        "MAILTRAP_TEST_INBOX_ID": "your_test_inbox_id"
      }
    }
  }
}

If you are using asdf for managing Node.js you should use absolute path to executable:

(example for Mac)

{
  "mcpServers": {
    "mailtrap": {
      "command": "/Users/<username>/.asdf/shims/node",
      "args": ["/path/to/mailtrap-mcp/dist/index.js"],
      "env": {
        "PATH": "/Users/<username>/.asdf/shims:/usr/bin:/bin",
        "ASDF_DIR": "/opt/homebrew/opt/asdf/libexec",
        "ASDF_DATA_DIR": "/Users/<username>/.asdf",
        "ASDF_NODEJS_VERSION": "20.6.1",
        "MAILTRAP_API_TOKEN": "your_mailtrap_api_token",
        "DEFAULT_FROM_EMAIL": "your_sender@example.com",
        "MAILTRAP_ACCOUNT_ID": "your_account_id",
        "MAILTRAP_TEST_INBOX_ID": "your_test_inbox_id"
      }
    }
  }
}

{
  "mcp": {
    "servers": {
      "mailtrap": {
        "command": "node",
        "args": ["/path/to/mailtrap-mcp/dist/index.js"],
        "env": {
          "MAILTRAP_API_TOKEN": "your_mailtrap_api_token",
          "DEFAULT_FROM_EMAIL": "your_sender@example.com",
          "MAILTRAP_ACCOUNT_ID": "your_account_id",
          "MAILTRAP_TEST_INBOX_ID": "your_test_inbox_id"
        }
      }
    }
  }
}

You can test the server using the MCP Inspector:

npm run dev

# Run the MCPB server directly
node dist/mcpb-server.js

# Or use the provided binary
mailtrap-mcpb-server

npm run dev:mcpb

This server uses structured error handling aligned with MCP conventions:

• VALIDATION_ERROR: Input validation failures
• CONFIGURATION_ERROR: Missing or invalid configuration
• EXECUTION_ERROR: Runtime execution errors
• TIMEOUT: Operation timeout (30 seconds default)

Errors include actionable messages and are logged in structured form.

• Input validated via Zod schemas
• Environment variables handled securely
• Timeout protection on operations (30 seconds)
• Sensitive details sanitized in error output

Structured JSON logs with levels: INFO, WARN, ERROR, DEBUG.

Enable debug logging by setting DEBUG=true.

# Example: enable debug logging
DEBUG=true node dist/mcpb-server.js

Important: The server writes logs to stderr so stdout remains reserved for JSON-RPC frames. This prevents hosts from encountering JSON parsing errors due to interleaved logs.

Log analysis example using jq:

# Filter error logs
node dist/mcpb-server.js 2>&1 | jq 'select(.level == "error")'

# Filter debug logs
node dist/mcpb-server.js 2>&1 | jq 'select(.level == "debug")'

Common issues:

1. Missing API Token: ensure MAILTRAP_API_TOKEN is set
2. Sandbox not working: verify MAILTRAP_TEST_INBOX_ID is configured
3. Timeout errors: check network connectivity and Mailtrap API status
4. Validation errors: ensure all required fields are provided

Bug reports and pull requests are welcome on GitHub. This project is intended to be a safe, welcoming space for collaboration, and contributors are expected to adhere to the code of conduct.

The package is available as open source under the terms of the MIT License.

Everyone interacting in the Mailtrap project's codebases, issue trackers, chat rooms and mailing lists is expected to follow the code of conduct.