What is ALT text and why is it important?
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Outlook blocks images by default for millions of recipients. When your beautifully designed email arrives and images don't load, what does your subscriber see? If your ALT text is blank, they see a grid of empty boxes. If you wrote it well, they see a text description of every image and they can still understand your offer, your CTA, and why they should care. That's the difference ALT text makes.
ALT text is the alt attribute on an HTML image tag: <img src="hero.jpg" alt="50% off spring sale, ends Sunday">. It's a plain text string that displays in place of the image when the image can't load, either because the email client blocks it by default or because the image file fails to fetch. It's also what screen readers announce to visually impaired subscribers in place of the image, making it one of the most practical accessibility improvements you can make to an email template.
The content of your ALT text should match the function of the image. For a hero image that says "Summer Sale: 30% off everything," your ALT text should say the same thing, not "hero image" or "banner." For a product image, describe the product: "Dark roast coffee beans in a kraft paper bag." For a purely decorative image (a divider line, a texture background) you should use an empty alt attribute (alt="") so screen readers skip it rather than announcing "decorative image." For a CTA button that's an image, your ALT text should mirror the button label exactly: "Shop Now," "Download the Guide," or whatever action you want the subscriber to take.
Three common mistakes are worth avoiding: leaving the alt attribute out entirely (which is different from an empty string and causes screen readers to fall back to reading the file name like "hero-2026-final-v3.jpg"), writing generic descriptions like "image" or "photo," and using ALT text as a dumping ground for keywords that don't describe what the image shows. Keep it literal and functional. If the image is communicating something, the ALT text should communicate the same thing in words.
To check your ALT text coverage before your next send, disable image loading in your email client and read through the email as if you're seeing it for the first time with no images. Does it still make sense? Can you find the CTA and understand the offer? If yes, you're in good shape. Review My Emails' template checker also flags images with missing or empty ALT attributes, so you can audit an entire template in one pass before it goes out to your list. Start there, then tackle the broader accessibility checklist once ALT text is solid.
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