How to write accessible ALT text?

Good alt text conveys the image's purpose, not just its appearance. Ask: if someone can't see this image, what do they need to know? For a product photo, that's the product name and key details. For a decorative divider, that's nothing (use empty alt).

Alt text guidelines: Be concise but complete-aim for under 125 characters. Describe function first-"Buy now button" not "blue rectangle." Include key information-product names, prices, CTAs. Skip redundancy-don't start with "Image of" or "Photo of." Use empty alt for decoration-alt="" tells screen readers to skip. Never omit the alt attribute-that's worse than empty.

Alt text is content strategy, not image description. You're deciding what information is essential for understanding the email. A hero image might need substantial alt text; an icon might need functional description; a decorative element needs none.