SMTP Smtp server and relay. Run docker run \ -p 25:25 \ -p 587:587 \ -e HOSTNAME=localhost.localdomain \ -e RELAY_SMTP_SERVER=smtprelay.example.com \ -e RELAY_SMTP_PORT=25 \ -e ALLOWED_SENDER_DOMAINS="" \ -e ALLOWED_NETWORKS="" \ bborbe/smtp:1.1.0