css-comments
CSS property · 15 supported, 3 partial, 0 unsupported across 21 clients
Client Support
| Client | Category | Engine | Support |
|---|---|---|---|
| Gmail | webmail | Gmail Web | Supported |
| Gmail Android | mobile | Gmail Mobile | Partial |
| Gmail iOS | mobile | Gmail Mobile | Supported |
| Outlook 365 | webmail | Outlook Web | Supported |
| Outlook (New) | desktop | Outlook Web | Supported |
| Outlook Classic | desktop | Microsoft Word | Supported |
| Outlook iOS | mobile | Outlook Mobile | Supported |
| Outlook Android | mobile | Outlook Mobile | Supported |
| Outlook for Mac | desktop | WebKit | Supported |
| Apple Mail | desktop | WebKit | Supported |
| Apple Mail iOS | mobile | WebKit | Supported |
| Yahoo Mail | webmail | Yahoo | Supported |
| Yahoo Mail Android | mobile | Yahoo | Partial |
| Yahoo Mail iOS | mobile | Yahoo | Partial |
| Samsung Mail | mobile | Samsung | Supported |
| Thunderbird | desktop | Gecko | Supported |
| HEY Mail | webmail | WebKit | Unknown |
| Proton Mail | webmail | Proton | Supported |
| AOL Mail | webmail | AOL | Supported |
| Fastmail | webmail | Fastmail | Unknown |
| Superhuman | desktop | Blink | Unknown |
Client-by-client behaviour for css-comments
Fully supports css-comments (15): Gmail, Gmail iOS, Outlook 365, Outlook (New), Outlook Classic, Outlook iOS, Outlook Android, Outlook for Mac, Apple Mail, Apple Mail iOS, Yahoo Mail, Samsung Mail, Thunderbird, Proton Mail, AOL Mail.
Partial support (3): Gmail Android, Yahoo Mail Android, Yahoo Mail iOS. Expect rendering quirks unique to each engine. Partial support typically means a subset of values, an ignored shorthand, or sanitizer-specific rewrites.
Behaviour unverified in: HEY Mail, Fastmail, Superhuman.
Fixes & Workarounds
Gmail Android
Partial"css-comments" is not supported in this email client.
Yahoo Mail Android
Partial"css-comments" is not supported in this email client.
Yahoo Mail iOS
Partial"css-comments" is not supported in this email client.
Related Features
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Try Emailens FreeSupport data last updated Apr 27, 2026 · synced from caniemail.com via @emailens/engine.