Definition
VML is the vector format Outlook understands for backgrounds. It is usually paired with conditional comments so only Outlook sees it.
Best Practices
- Use VML for bulletproof full-bleed backgrounds in Outlook.
- Keep a CSS background fallback for modern clients.
- Test VML in Outlook because small errors render as broken images.
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Frequently Asked Questions
Outlook ignores CSS backgrounds on many elements; VML paints them for Outlook.
Yes, for Outlook desktop compatibility.
Yes, provide both and let conditionals pick.