CSS Properties

margin

CSS property · 9 supported, 12 partial, 0 unsupported across 21 clients

margin splits the field: 9 full, 12 partial of 21 clients as of Sep 2, 2026, the partials (Gmail, Gmail Android, Gmail iOS) are where sends go wrong.

3/7 webmail, 4/6 desktop, 2/8 mobile clients support margin fully.
Partial in Gmail, Gmail Android, Gmail iOS, Outlook 365 and 8 more, behavior differs from browsers, test before relying on it.
Outlook Classic (Word engine, supported to at least 2029) does not fully support margin, 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 Oct 1, 2019, synced by Emailens Sep 2, 2026.

margin controls external spacing around block-level elements and is notably less reliable in email than padding. Outlook on Windows ignores margin on most elements, so production email layouts typically substitute margin with padded <td> cells. Modern clients honor margin correctly, but the lowest-common-denominator approach is to avoid it entirely for structural spacing.

Client Support

Client	Category	Engine	Support
Gmail	webmail	Gmail Web	Partial^{See caveat 1}
Gmail Android	mobile	Gmail Mobile	Partial^{See caveat 1}
Gmail iOS	mobile	Gmail Mobile	Partial^{See caveat 1}
Outlook 365	webmail	Outlook Web	Partial^{See caveat 1}
Outlook (New)	desktop	Outlook Web	Partial^{See caveat 2}
Outlook Classic	desktop	Microsoft Word	Partial^{See caveat 3}
Outlook iOS	mobile	Outlook Mobile	Partial^{See caveat 1}
Outlook Android	mobile	Outlook Mobile	Partial^{See caveat 1}
Outlook for Mac	desktop	WebKit	Supported
Apple Mail	desktop	WebKit	Supported
Apple Mail iOS	mobile	WebKit	Supported
Yahoo Mail	webmail	Yahoo	Partial^{See caveat 1}
Yahoo Mail Android	mobile	Yahoo	Partial^{See caveat 1}
Yahoo Mail iOS	mobile	Yahoo	Partial^{See caveat 1}
Samsung Mail	mobile	Samsung	Supported
Thunderbird	desktop	Gecko	Supported
HEY Mail	webmail	WebKit	Supported
Proton Mail	webmail	Proton	Supported
AOL Mail	webmail	AOL	Partial^{See caveat 1}
Fastmail	webmail	Fastmail	Supported
Superhuman	desktop	Blink	Supported

Documented caveats (3)

1.Gmail, Gmail Android, Gmail iOS, Outlook 365, Outlook iOS, Outlook Android, Yahoo Mail, Yahoo Mail Android, Yahoo Mail iOS, AOL Mail: Partial. Negative values are not supported.
2.Outlook (New): Partial. Negative values are not supported. Partial. Not supported on <span> and <body> elements. Buggy. background-color is included inside the margin. Partial. auto value is not supported.
3.Outlook Classic: Partial. Negative values are not supported. Partial. Not supported on <span> and <body> elements. Buggy. background-color is included inside the margin.

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

Client-by-client behaviour for margin

Fully supports margin (9): Outlook for Mac, Apple Mail, Apple Mail iOS, Samsung Mail, Thunderbird, HEY Mail, Proton Mail, Fastmail, Superhuman.

Partial support (12): Gmail, Gmail Android, Gmail iOS, Outlook 365, Outlook (New), Outlook Classic, Outlook iOS, Outlook Android, Yahoo Mail, Yahoo Mail Android, Yahoo Mail iOS, AOL Mail. Expect rendering quirks unique to each engine. Partial support typically means a subset of values, an ignored shorthand, or sanitizer-specific rewrites.

When to use margin in email

Centering an outer table by setting margin: 0 auto on the table element when targeting modern clients only.
Adding small gaps between inline-block elements in mobile-first templates.
Resetting default margins on block elements like <p>, <h1>, and <ul> via inline overrides.

Rendering behaviour and edge cases

Outlook on Windows ignores margin on table elements, breaking centering tricks unless you use align="center" and a fixed width.
Gmail strips negative margin values entirely, making margin-based off-canvas tricks unreliable.
Some clients add extra default margin on <p> tags , explicitly set margin: 0 on every paragraph that needs predictable spacing.

Recommended fallback strategy

Replace structural margin with padded table cells for cross-client consistency. Use margin only for resetting browser defaults on block elements, and always set explicit margin: 0 on <p>, <h1>–<h6>, and <ul> to prevent client-default spacing from pushing your layout.