font-kerning
CSS property · 12 supported, 0 partial, 5 unsupported across 21 clients
12 of 21 email clients render font-kerning fully (Sep 2, 2026 data); it breaks outright in Outlook (New), Yahoo Mail, Yahoo Mail Android and 2 more.
- 3/7 webmail, 3/6 desktop, 6/8 mobile clients support font-kerning fully.
- Unsupported in Outlook (New), Yahoo Mail, Yahoo Mail Android, Yahoo Mail iOS and 1 more.
- Outlook Classic (Word engine, supported to at least 2029) does not fully support font-kerning, and its replacement changes little here; see the deprecation diff.
- Across all clients, only 6 of 298 tracked HTML/CSS features render identically everywhere.
Source: caniemail.com (MIT), via the Emailens engine. Last tested upstream Aug 1, 2022, synced by Emailens Sep 2, 2026.
Client Support
| Client | Category | Engine | Support |
|---|---|---|---|
| Gmail | webmail | Gmail Web | Supported |
| Gmail Android | mobile | Gmail Mobile | Supported |
| Gmail iOS | mobile | Gmail Mobile | Supported |
| Outlook 365 | webmail | Outlook Web | Supported |
| Outlook (New) | desktop | Outlook Web | Unsupported |
| Outlook Classic | desktop | Microsoft Word | Unknown |
| 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 | Unsupported |
| Yahoo Mail Android | mobile | Yahoo | Unsupported |
| Yahoo Mail iOS | mobile | Yahoo | Unsupported |
| Samsung Mail | mobile | Samsung | Supported |
| Thunderbird | desktop | Gecko | Supported |
| HEY Mail | webmail | WebKit | Unknown |
| Proton Mail | webmail | Proton | Supported |
| AOL Mail | webmail | AOL | Unsupported |
| Fastmail | webmail | Fastmail | Unknown |
| Superhuman | desktop | Blink | Unknown |
Client-by-client behaviour for font-kerning
Fully supports font-kerning (12): Gmail, Gmail Android, Gmail iOS, Outlook 365, Outlook iOS, Outlook Android, Outlook for Mac, Apple Mail, Apple Mail iOS, Samsung Mail, Thunderbird, Proton Mail.
No support (5): Outlook (New), Yahoo Mail, Yahoo Mail Android, Yahoo Mail iOS, AOL Mail. Plan fallbacks for these clients before relying on font-kerning in production sends.
Behaviour unverified in: Outlook Classic, HEY Mail, Fastmail, Superhuman.
Fixes & Workarounds
Outlook (New)
Unsupported"font-kerning" is not supported in this email client.
Yahoo Mail
Unsupported"font-kerning" is not supported in this email client.
Yahoo Mail Android
Unsupported"font-kerning" is not supported in this email client.
Yahoo Mail iOS
Unsupported"font-kerning" is not supported in this email client.
AOL Mail
Unsupported"font-kerning" is not supported in this email client.
Related Features
Check your own HTML for font-kerning
Paste your own, or run the sample below. Analyzed in this page, with no signup and nothing stored.
Test your font-kerning layout across 21 email clients
Preview rendering, catch CSS issues, and see how font-kerning displays across Outlook, Gmail, and Apple Mail. Free, no account needed.
Instant live preview · No signup required · 21 email engines
Last tested upstream: · Last synced by Emailens:
caniemail.com (MIT) records Aug 1, 2022 as the last time font-kerning was tested in a real client, 4 years before this sync. Syncing copies that result forward, it does not re-test it. Carried in @emailens/engine data v0.12.2.