HTML Elements

<input type="checkbox">

HTML element · 15 supported, 1 partial, 4 unsupported across 21 clients

15 of 21 email clients render <input type="checkbox"> fully (Sep 2, 2026 data); it breaks outright in Outlook (New), Outlook Classic, HEY Mail and 1 more.

5/7 webmail, 2/6 desktop, 8/8 mobile clients support <input type="checkbox"> fully.
Unsupported in Outlook (New), Outlook Classic, HEY Mail, Proton Mail.
Partial in Thunderbird, behavior differs from browsers, test before relying on it.
Outlook Classic (Word engine, supported to at least 2029) does not fully support <input type="checkbox">, 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 Sep 10, 2019, 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	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	Partial^{See caveat 1}
HEY Mail	webmail	WebKit	Unsupported
Proton Mail	webmail	Proton	Unsupported
AOL Mail	webmail	AOL	Supported
Fastmail	webmail	Fastmail	Supported
Superhuman	desktop	Blink	Unknown

Documented caveats (1)

1.Thunderbird: Buggy. Interacting with the element submits the form it belongs in.

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

Client-by-client behaviour for <input type="checkbox">

Fully supports <input type="checkbox"> (15): Gmail, Gmail Android, Gmail iOS, Outlook 365, Outlook iOS, Outlook Android, Outlook for Mac, Apple Mail, Apple Mail iOS, Yahoo Mail, Yahoo Mail Android, Yahoo Mail iOS, Samsung Mail, AOL Mail, Fastmail.

Partial support (1): Thunderbird. Expect rendering quirks unique to each engine. Partial support typically means a subset of values, an ignored shorthand, or sanitizer-specific rewrites.

No support (4): Outlook (New), Outlook Classic, HEY Mail, Proton Mail. Plan fallbacks for these clients before relying on <input type="checkbox"> in production sends.

Behaviour unverified in: Superhuman.