Quick Overview
Email clients vary significantly in their support for modern HTML and CSS features. This matrix shows support for key features that matter most for responsive, well-designed HTML emails.
✓Supported across all versions
◐Partially supported or version-dependent
✗Not supported
Feature Support by Email Client
Click any email client name to view detailed compatibility information.
| Feature | AOL | Apple Mail | Fastmail | Free.fr | Gmail | GMX | Hey | IONOS 1&1 | La Poste | Mail.ru | Orange Mail | Outlook | ProtonMail | Rainloop | Samsung Email | SFR | T-Online | Thunderbird | Web.de | WP.pl | Yahoo Mail |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Media Queries css-at-media-orientation | ✗ | ◐ | ✓ | ? | ◐ | ✓ | ✓ | ✓ | ◐ | ✓ | ◐ | ◐ | ✗ | ? | ◐ | ◐ | ? | ◐ | ✓ | ? | ✗ |
| Dark Mode Support css-color-scheme | ✗ | ✓ | ✗ | ? | ✗ | ✗ | ✗ | ? | ? | ✗ | ? | ✗ | ◐ | ? | ✓ | ◐ | ✗ | ✓ | ✗ | ? | ✗ |
| Flexbox css-display-flex | ◐ | ✓ | ✓ | ? | ◐ | ◐ | ✓ | ✓ | ✓ | ✓ | ◐ | ◐ | ✓ | ? | ✓ | ✓ | ? | ✓ | ◐ | ? | ◐ |
| CSS Grid css-display-grid | ✗ | ✓ | ✓ | ? | ◐ | ◐ | ✓ | ✓ | ✓ | ✓ | ◐ | ◐ | ✓ | ? | ✓ | ✓ | ? | ✓ | ◐ | ? | ✗ |
| Web Fonts css-at-font-face | ✗ | ✓ | ✗ | ? | ✗ | ◐ | ✓ | ◐ | ◐ | ✗ | ◐ | ◐ | ◐ | ? | ✓ | ◐ | ? | ✓ | ◐ | ? | ✗ |
| Animations css-animation | ✗ | ✓ | ✓ | ? | ✗ | ◐ | ✓ | ◐ | ◐ | ✗ | ✗ | ◐ | ✗ | ? | ✓ | ◐ | ? | ✓ | ◐ | ? | ✗ |
| Gradients css-linear-gradient | ✗ | ✓ | ✓ | ✓ | ◐ | ◐ | ✓ | ✓ | ✓ | ✓ | ✗ | ◐ | ✓ | ? | ◐ | ✓ | ✓ | ✓ | ◐ | ? | ✗ |
| CSS Transforms css-transform | ✗ | ✓ | ✓ | ? | ✗ | ◐ | ✓ | ✓ | ✓ | ✗ | ◐ | ◐ | ✓ | ? | ✓ | ✓ | ? | ✓ | ◐ | ? | ✗ |
Key Findings
- Samsung Email, Apple Mail, and Thunderbird lead support: These clients support 79–81% of tested CSS properties, making them the most capable rendering engines in our dataset
- Outlook (Windows) is the most limited: At 15% support, Outlook's Word rendering engine is the primary constraint for HTML email compatibility — design decisions are often made around Outlook first
- Gmail is more restrictive than commonly assumed: Gmail supports only 27% of tested CSS properties. Web fonts, animations, and many layout features are stripped or unsupported across platforms
- Dark mode CSS is not widely supported: Only Apple Mail, Samsung Email, and Thunderbird reliably support
color-schemeandprefers-color-scheme. Gmail, Yahoo, AOL, and ProtonMail do not support these properties - European and open-source clients cluster in the middle: Fastmail, GMX, Web.de, and similar clients generally fall in the 40–65% range, with inconsistent support for advanced layout features
Next Steps
- CSS Support Matrix - See detailed CSS property compatibility
- Email Client Quirks Database - Discover client-specific rendering issues and workarounds
- Blog Articles - Read in-depth guides on specific features and best practices