The message should survive its decoration.
Turn the images off
The offer, sender, expiry, and primary action remain understandable without relying on artwork or text baked into a picture.
Follow the keyboard
Reading order, focus visibility, link labels, and any interactive fallback are checked in the delivered email and landing page.
Keep a plain-text twin
The alternate version carries the same facts and choices without becoming an unedited wall of tracking links.
