Image-only emails trigger spam filters because they can't read pictures. Keep at least 40% of your email as text, or write detailed alt text if images are unavoidable. Poor alt text makes it worse.
Don't send image-only emails. Blend at least 40% text to image. And if you really, really care and you're so good at audience segmentation and you're sending image-only emails, make sure you're filling in the alt text. It bothers me the worst when the alt text is not filled in well because that's the only thing that's readable by the spam filters at this point. Subscribe to the pod.
