Composition

ALT Text in Email: Why It Matters and How to Write It

Updated September 2026 · 6 min read

In short

ALT text is the text description of an image, displayed when the image cannot be shown and read aloud by screen readers. In email, it preserves the message when images are blocked — a common default in many email clients — and it gives mailbox providers text to understand what you send.

Why ALT text matters in email campaigns

Unlike the web, email is an environment where images frequently do not load: blocked by default, slow connections, corporate security settings. Without ALT text, those recipients see empty frames — no offer, no CTA, no message.

Add screen reader users, for whom ALT text is the image, and the stakes become clear. It also matters upstream: mailbox providers analyzing your email need text to understand what you are sending.

ALT text is not a technical detail. It is the fallback version of your campaign.

How to write useful ALT text

Describe what the image does in the email, not what it looks like. Ask yourself: if this image disappeared, what would the reader need to know to keep going?

ImageWeak ALTUseful ALT
Hero with offeralt="banner1.jpg"alt="Autumn sale: 30% off all coats until Sunday"
Button as imagealt="button"alt="Shop the sale"
Logoalt="logo"alt="Your Brand"
Decorative dividerno ALT attributealt=""

How to read an ALT text check

PassAll or nearly all images — at least 80% — carry a valid ALT attribute.
WarnSome images are missing ALT attributes.
FailFew images (40% or less) or none carry an ALT attribute.

5 best practices

  1. Test your email with images disabled: the message, offer and CTA should still come through.
  2. Write short, descriptive ALT text focused on function and context — not a file name or a repeated keyword.
  3. Give decorative images an empty ALT (alt="") rather than removing the attribute: screen readers will skip them cleanly.
  4. Prioritize the images that carry meaning: hero, product visuals, buttons rendered as images.
  5. Ask someone unfamiliar with the campaign to read only the ALT texts. If the message holds, your fallback works.

Common mistakes

  • Removing the ALT attribute on decorative images instead of leaving it empty — some screen readers then read the file name aloud.
  • Locking the whole offer (price, dates, promo code) inside a single image.
  • Forgetting buttons rendered as images: without ALT, the call to action simply disappears.
  • Starting with “Image of…”: screen readers already announce that it is an image.
  • Placing key information in a CSS background image, which cannot carry ALT text at all.
Inside Inbox Maestro

How Inbox Maestro checks it

Inbox Maestro counts every image in your test email, measures ALT completion and identifies exactly which visuals would leave your message empty when images fail to load — background images included, flagged separately since they cannot carry ALT text. The result appears in the Checkup section of your report, under Composition.

Checkup › Composition
Checked on every test email, as recipients will display it.
Email Weight
Pass
Mobile Loading Speed
Pass
Alternative Text7 of 10 images described
Warn
Text-to-Image Ratio
Pass
Font-Size Review
Pass
Color Contrast Accessibility
Pass
Example result. The missing images are listed one by one, so the fix is a matter of minutes.

Frequently asked questions

What is ALT text in email?

The text alternative of an image, shown when the image cannot load and read by screen readers. In email it acts as the fallback version of your visual content.

Do all images need ALT text?

All meaningful images do. Purely decorative images should carry an empty ALT (alt="") so assistive technologies skip them without noise.

Does missing ALT text affect deliverability?

It can contribute negatively: providers rely on text to interpret content, and an email whose message is locked inside images is harder to classify as legitimate.

How long should email ALT text be?

A few words to a short sentence — enough to convey the image's function in context. Description beats repetition, and specificity beats keywords.

Can background images have ALT text?

No. CSS background images cannot carry an ALT attribute, so any essential information placed in a background image should also appear in live text.

See your campaign the way an image-blocking client sees it.

Inbox Maestro measures ALT completion on your test email and flags the visuals that leave your message empty when images don't load.

Get Your Email Checkup →