When should you use Images have usable alt text?
email-image-alt-text · functional · recommended
When should you use this check?
Run this on every image-bearing send, because for a large share of your recipients the alt text *is* the email — your first message to any Outlook address renders with images off until they add you to their Safe Senders list. That means a hero and a call to action with empty alt attributes render as blank rectangles to exactly the prospects you are trying to win. It is a source-level check, so it covers every image in the message rather than the ones that happen to be visible in a proof.
When should you not?
Skip it on mail with no meaningful imagery. Note also that decorative images legitimately carry empty alt text — a spacer or a background flourish should be silent to a screen reader — so if your template is mostly decorative the findings will need triage rather than blanket fixing. It is not the check for whether the message as a whole still makes sense with images blocked; that is the images-off legibility check, and it asks a harder question this one cannot.
What does it inspect?
Every image must carry an alt attribute: informative images with real alternative text (not filenames, URLs, or placeholders), decorative images marked alt="", and image-only links must keep an accessible name. Spacers and tracking pixels are ignored.
What does a failure mean?
A failure means at least one image has no alt text, or has alt text that says nothing useful — one of the placeholder values that means someone filled the field to satisfy a tool. The consequence is concentrated rather than spread: screen reader users lose that content entirely, and every recipient with images blocked sees a blank space where your offer was. On a hero or a button the failure is total, which is why those are worth checking even when the rest of the template is decorative.
What are the Standard defaults — and why?
Two parameters carry the check. `placeholderAltTexts` lists the values that count as filled-but-useless — `image`, `img`, `photo`, `picture`, `graphic`, `icon`, `spacer`, `banner`, `untitled`, `alt text`, `placeholder` — chosen because they appear in real templates and never actually describe anything. `visualAltTextReview` defaults to `false`: it is a deliberate opt-in because it costs a model call, and what it buys is accessibility and images-off legibility rather than deliverability.
How does an agent call it?
{
"type": "email",
"validations": [
"email-image-alt-text"
]
}
Who governs the Standard?
Schemafirst.org publishes community-governed standards for digital QA. ArbiterQA is a sponsor and commercial licensee of those standards; citation does not mean Schemafirst operates ArbiterQA.
Author ArbiterQA · Reviewed by ArbiterQA · 2026-08-14