Mail Relay Deployment

Deploys a lightweight Postfix mail relay based on mwader/postfix-relay. It accepts unauthenticated local emails on port 25, rewrites all sender addresses to a defined address, and securely relays the emails to an upstream SMTP provider.

Features

• Accepts unqualified senders and all recipients from internal networks.
• Accepts SMTP requests without TLS and authentication.
• Optionally accepts inbound TLS requests (generates a self-signed certificate on startup).
• Relays outbound emails via authenticated SMTP over TLS.
• Rewrites envelope senders and From: headers dynamically based on .env configuration.

Prerequisites

• A working Docker host.
• Port 25 must be available. On Debian hosts, disable the default MTA:

  sudo systemctl stop exim4
  sudo systemctl disable exim4

Deployment

1. Prepare the deployment directory:

   sudo mkdir -p /opt/mailrelay
   sudo chown $USER:$USER /opt/mailrelay
   cd /opt/mailrelay
   
   git clone git@github.com:sdrwtf-labs/mailrelay-deployment.git .

2. Make the wrapper script executable:

   chmod +x wrapper.sh

3. Configure the environment variables:

   cp .env.example .env
   nano .env

4. Start the service:

   docker compose up -d

Continuous Deployment

This repository is configured for automated deployments via GitHub Actions. Pushes to the main branch will trigger an SSH action to pull the latest code and recreate the container. Ensure the SSH_PRIVATE_KEY secret is configured in the repository settings.