Never send an email that is one big image. It will be blocked by many email clients, you won’t get full tracking capability of link engagement, and you run a higher risk of landing in spam filters.
You also don’t want to send emails that are extra heavy on graphics and light on text. Aim for a ratio of around 60% text and 40% graphics.
[...] Text to Image Ratio [...]
[...] Text to Image Ratio: In this email, the ratio is to heavy on images. This creates problems, as many email clients will block images by default. [...]
[...] one big image: We’ve discussed this several times before, but pay attention to your text to image ratio and don’t create a single image for your entire [...]