SMTP to Datadog

A lightweight Python SMTP server that receives emails and forwards their content to Datadog's logs API.

Perfect for monitoring application emails, or creating email-based logging pipelines.

Quick Start

# Create virtual environment and install dependencies
python3 -m venv .venv
source .venv/bin/activate
pip install -r requirements.txt

# Start the server
DATADOG_API_KEY=your_api_key_here python3 smtp2datadog.py

# In another terminal, send a test email
python3 send_test_email.py

Features

• Asynchronous SMTP server using aiosmtpd
• Parses incoming emails (subject, body, headers)
• Sends structured logs to Datadog Logs API
• Configurable via environment variables
• Handles both plain text and multipart emails
• Test script included

Installation

1. Clone this repository

2. Create a virtual environment and install dependencies:

python3 -m venv .venv
source .venv/bin/activate
pip install -r requirements.txt

Configuration

Configuration is done via environment variables:

• DATADOG_API_KEY: Your Datadog API key (required)
• DATADOG_SITE: Your Datadog site (default: datadoghq.com)
  • US1: datadoghq.com
  • US3: us3.datadoghq.com
  • US5: us5.datadoghq.com
  • EU: datadoghq.eu
  • AP1: ap1.datadoghq.com
• SERVICE_NAME: Service name for tagging logs (default: smtp2datadog)
• SMTP_HOST: Host to bind the SMTP server (default: localhost)
• SMTP_PORT: Port for the SMTP server (default: 1025)

See .env.example for reference.

Usage

Running the server

Linux/macOS:

# Export environment variable
export DATADOG_API_KEY=your_api_key_here
python3 smtp2datadog.py

# Or inline
DATADOG_API_KEY=your_api_key_here python3 smtp2datadog.py

Windows (Command Prompt):

set DATADOG_API_KEY=your_api_key_here
python smtp2datadog.py

Windows (PowerShell):

$env:DATADOG_API_KEY="your_api_key_here"
python smtp2datadog.py

Sending test emails

Use the included test script:

python3 send_test_email.py

Or send emails manually using the swaks tool:

swaks --to test@example.com \
      --from sender@example.com \
      --server localhost:1025 \
      --header "Subject: Test Email" \
      --body "This is a test message"

Log Format

Emails are sent to Datadog with the following structure:

{
  "ddsource": "smtp",
  "ddtags": "service:smtp2datadog,env:production",
  "hostname": "client-hostname",
  "message": "Email from sender@example.com: Subject Line",
  "email": {
    "from": "sender@example.com",
    "to": "recipient@example.com",
    "subject": "Subject Line",
    "body": "Email body content",
    "date": "Mon, 25 Oct 2025 12:00:00 +0000",
    "recipients": ["recipient@example.com"],
    "mail_from": "sender@example.com"
  },
  "timestamp": "2025-10-25T12:00:00.000000Z"
}

Viewing Logs in Datadog

1. Go to Datadog Logs Explorer
2. Filter by source:smtp or service:smtp2datadog
3. You can create custom facets on the email.* fields for better filtering

Security

This server has NO authentication.

• By default, the server binds to localhost and is only accessible from the local machine

Use Case

• Converting application emails to Datadog logs for centralized monitoring

License

MIT