Identify Critical Points: Determine which components of your email system are critical for successful delivery. Develop Scenarios: Create scenarios where each of these critical points fails. For example, what happens if your primary SMTP provider fails? Implement Backup Systems: Set up backup systems for each critical point. This could involve secondary servers, alternative SMTP providers, and backup DNS settings. Test Regularly: Regularly test these backup systems to ensure they work as expected. This can be done by temporarily disabling the primary system and observing if the backup system takes over seamlessly.