text-underline-position
CSS property · 7 supported, 4 partial, 7 unsupported across 21 clients
As of Sep 2, 2026, text-underline-position fails or degrades in 14 of 21 email clients, treat it as progressive enhancement, never structure.
- 3/7 webmail, 1/6 desktop, 3/8 mobile clients support text-underline-position fully.
- Unsupported in Outlook (New), Outlook Classic, Outlook for Mac, Yahoo Mail and 3 more.
- Partial in Gmail iOS, Outlook iOS, Apple Mail, Apple Mail iOS, behavior differs from browsers, test before relying on it.
- Outlook Classic (Word engine, supported to at least 2029) does not fully support text-underline-position, 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 Dec 8, 2023, 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 | PartialSee caveat 1 |
| Outlook 365 | webmail | Outlook Web | Supported |
| Outlook (New) | desktop | Outlook Web | Unsupported |
| Outlook Classic | desktop | Microsoft Word | Unsupported |
| Outlook iOS | mobile | Outlook Mobile | PartialSee caveat 1 |
| Outlook Android | mobile | Outlook Mobile | Supported |
| Outlook for Mac | desktop | WebKit | Unsupported |
| Apple Mail | desktop | WebKit | PartialSee caveat 1 |
| Apple Mail iOS | mobile | WebKit | PartialSee caveat 1 |
| 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 |
Documented caveats (1)
- 1.Gmail iOS, Outlook iOS, Apple Mail, Apple Mail iOS: Partial. Supports
underbut notrightandleft
Caveats recorded by caniemail.com (MIT) and carried verbatim, one entry per wording rather than per client.
Client-by-client behaviour for text-underline-position
Fully supports text-underline-position (7): Gmail, Gmail Android, Outlook 365, Outlook Android, Samsung Mail, Thunderbird, Proton Mail.
Partial support (4): Gmail iOS, Outlook iOS, Apple Mail, Apple Mail iOS. Expect rendering quirks unique to each engine. Partial support typically means a subset of values, an ignored shorthand, or sanitizer-specific rewrites.
No support (7): Outlook (New), Outlook Classic, Outlook for Mac, Yahoo Mail, Yahoo Mail Android, Yahoo Mail iOS, AOL Mail. Plan fallbacks for these clients before relying on text-underline-position in production sends.
Behaviour unverified in: HEY Mail, Fastmail, Superhuman.
Fixes & Workarounds
Outlook (New)
Unsupported"text-underline-position" is not supported in this email client.
Outlook Classic
Unsupported"text-underline-position" is not supported in this email client.
Outlook for Mac
Unsupported"text-underline-position" is not supported in this email client.
Yahoo Mail
Unsupported"text-underline-position" is not supported in this email client.
Yahoo Mail Android
Unsupported"text-underline-position" is not supported in this email client.
Yahoo Mail iOS
Unsupported"text-underline-position" is not supported in this email client.
AOL Mail
Unsupported"text-underline-position" is not supported in this email client.
Gmail iOS
Partial"text-underline-position" is not supported in this email client.
Outlook iOS
Partial"text-underline-position" is not supported in this email client.
Apple Mail
Partial"text-underline-position" is not supported in this email client.
Apple Mail iOS
Partial"text-underline-position" is not supported in this email client.
Related Features
Check your own HTML for text-underline-position
Paste your own, or run the sample below. Analyzed in this page, with no signup and nothing stored.
Test your text-underline-position layout across 21 email clients
Preview rendering, catch CSS issues, and see how text-underline-position 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 Dec 8, 2023 as the last time text-underline-position was tested in a real client, 2 years before this sync. Syncing copies that result forward, it does not re-test it. Carried in @emailens/engine data v0.12.2.