Definition
Email background image fallback is the practice of defining a solid background colour or alternative visual treatment that displays when a CSS background image cannot or does not load. Since many email clients — including Outlook for desktop and Gmail with images turned off — do not render CSS background images, fallback colours prevent text from becoming invisible against a missing image.
For example, a hero section with white text on a dark photographic background needs a dark fallback colour. Without it, the white text renders against the default white or grey background and becomes unreadable. The fallback colour is defined alongside the background image in the same CSS declaration.
Implementation
Background images in HTML email are typically set using the CSS background or background-image property with a fallback background-color. The inline style background: #2d3748 url('hero.jpg') center/cover no-repeat ensures that the dark colour #2d3748 is visible whenever the image does not load.
Best Practices
- Always pair a background image with a background colour that provides sufficient contrast for any text placed on top
- Test emails with images disabled across Outlook, Gmail and Apple Mail before sending
- For critical content — CTAs, headlines, key information — avoid placing text over background images entirely; use solid-colour sections instead
Related Glossary Terms
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Email Accessibility Guidelines
Email accessibility guidelines ensure emails are usable by people with disabilities, following WCAG standards for screen readers, colour contrast, keyboard navigation, and readable content.
Email Accessibility
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