All of our notification emails that reference images uploaded to our AWS still fail to display when viewed using the Mail app built in to iOS.
The daily summary emails display the images fine - which I don’t understand. They must be embedded or referenced differently somehow.
Here’s what all iOS users see:
As a test, I’d like to add https: to the start of the image src url as I think this may solve the problem:
Does anyone know how I could do that? 
Would adding https: to the img src url cause issues elsewhere?