Definition
Conditional comments are wrapped in special comment syntax Outlook understands. They let developers ship Outlook-specific tables, styles and VML.
Best Practices
- Wrap Outlook-only markup in conditional comment blocks.
- Provide a modern fallback outside the conditional.
- Validate the final HTML to catch unclosed conditional comments.
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Frequently Asked Questions
They are treated as comments by non-Outlook clients, so yes.
Yes, using version-aware conditionals.
No, they are ignored there, which is the point.