Today, we launched a new feature to every app called “Fallback”.
In rare situations, an email may not be able to communicate with our servers making your dynamic image assets unavailable. In this scenario, a static fallback image is served instead. The default for every app is a single invisible pixel.
Adding a custom fallback image ensures that an attractive and properly sized image will always show up. Image fallback is available for all our plans. We suggest you take a few minutes to set this up for your mission-critical email apps.
Fallback button on an app edit page: