HTML email preflight guide
Email accessibility checks you can run before send
A source preflight can catch missing names and structural clues, but it cannot replace testing the actual delivered message with assistive technology and representative inbox clients.
Set the document language
Include a useful lang value on the HTML element so compatible assistive technology has a pronunciation signal.
Name informative images and links
Provide meaningful alternative text for informative images and accessible names for links. Use an intentional empty alt value only for decorative images.
Keep the heading outline coherent
Avoid unexpected jumps in heading level and make sure the source order still makes sense when styling is removed.
Check deterministic contrast, then review
Inline foreground and background colors can support a reproducible contrast calculation. Background images, client transformations and the final message still require visual review.