CSS Properties

modern-color

CSS property · 5 supported, 0 partial, 14 unsupported across 21 clients

As of Sep 2, 2026, modern-color fails or degrades in 16 of 21 email clients, treat it as progressive enhancement, never structure.

2/7 webmail, 2/6 desktop, 1/8 mobile clients support modern-color fully.
Unsupported in Gmail, Gmail Android, Gmail iOS, Outlook 365 and 10 more.
Outlook Classic (Word engine, supported to at least 2029) does not fully support modern-color, 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 Jan 18, 2023, synced by Emailens Sep 2, 2026.

Client Support

Client	Category	Engine	Support
Gmail	webmail	Gmail Web	Unsupported^{See caveat 1}
Gmail Android	mobile	Gmail Mobile	Unsupported^{See caveat 1}
Gmail iOS	mobile	Gmail Mobile	Unsupported^{See caveat 1}
Outlook 365	webmail	Outlook Web	Unsupported
Outlook (New)	desktop	Outlook Web	Unsupported
Outlook Classic	desktop	Microsoft Word	Unknown
Outlook iOS	mobile	Outlook Mobile	Unsupported
Outlook Android	mobile	Outlook Mobile	Unsupported
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	Unsupported
Thunderbird	desktop	Gecko	Unsupported
HEY Mail	webmail	WebKit	Supported^{See caveat 2}
Proton Mail	webmail	Proton	Unsupported
AOL Mail	webmail	AOL	Unsupported
Fastmail	webmail	Fastmail	Supported^{See caveat 2}
Superhuman	desktop	Blink	Unknown

Documented caveats (2)

1.Gmail, Gmail Android, Gmail iOS: Using this syntax for an inline style will remove all inline styles applied to that element.
2.HEY Mail, Fastmail: Depends on browser support.

Caveats recorded by caniemail.com (MIT) and carried verbatim, one entry per wording rather than per client.

Client-by-client behaviour for modern-color

Fully supports modern-color (5): Outlook for Mac, Apple Mail, Apple Mail iOS, HEY Mail, Fastmail.

No support (14): Gmail, Gmail Android, Gmail iOS, Outlook 365, Outlook (New), Outlook iOS, Outlook Android, Yahoo Mail, Yahoo Mail Android, Yahoo Mail iOS, Samsung Mail, Thunderbird, Proton Mail, AOL Mail. Plan fallbacks for these clients before relying on modern-color in production sends.

Behaviour unverified in: Outlook Classic, Superhuman.