caption-side
CSS property · 20 supported, 0 partial, 1 unsupported across 21 clients
caption-side is safe in 20 of 21 email clients as of Oct 14, 2026, the holdout is Outlook Classic.
- 7/7 webmail, 5/6 desktop, 8/8 mobile clients support caption-side fully.
- Unsupported in Outlook Classic.
- Outlook Classic (Word engine, supported to at least 2029) does not fully support caption-side, one of the few features its replacement actually fixes; 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 May 13, 2021, synced by Emailens Oct 14, 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 | Supported |
| Outlook Classic | desktop | Microsoft Word | Unsupported |
| 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 | Supported |
| Yahoo Mail iOS | mobile | Yahoo | Supported |
| Samsung Mail | mobile | Samsung | Supported |
| Thunderbird | desktop | Gecko | Supported |
| HEY Mail | webmail | WebKit | SupportedSee caveat 1 |
| Proton Mail | webmail | Proton | Supported |
| AOL Mail | webmail | AOL | Supported |
| Fastmail | webmail | Fastmail | Supported |
| Superhuman | desktop | Blink | Supported |
Documented caveats (1)
- 1.HEY Mail: The
caption-sideproperty in CSS is supported but the<caption>HTML element is not.
Caveats recorded by caniemail.com (MIT) and carried verbatim, one entry per wording rather than per client.
Client-by-client behaviour for caption-side
Fully supports caption-side (20): Gmail, Gmail Android, Gmail iOS, Outlook 365, Outlook (New), Outlook iOS, Outlook Android, Outlook for Mac, Apple Mail, Apple Mail iOS, Yahoo Mail, Yahoo Mail Android, Yahoo Mail iOS, Samsung Mail, Thunderbird, HEY Mail, Proton Mail, AOL Mail, Fastmail, Superhuman.
No support (1): Outlook Classic. Plan fallbacks for these clients before relying on caption-side in production sends.
Fixes & Workarounds
Outlook Classic
Unsupported"caption-side" is not supported in this email client.
Related Features
Check your own HTML for caption-side
Paste your own, or run the sample below. Analyzed in this page, with no signup and nothing stored.
Test your caption-side layout across 21 email clients
Preview rendering, catch CSS issues, and see how caption-side 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 May 13, 2021 as the last time caption-side was tested in a real client, 5 years before this sync. Syncing copies that result forward, it does not re-test it. Carried in @emailens/engine data v0.14.5.