CSS Properties

transition

CSS property · 4 supported, 7 partial, 10 unsupported across 21 clients

As of Sep 2, 2026, transition fails or degrades in 17 of 21 email clients, treat it as progressive enhancement, never structure.

1/7 webmail, 2/6 desktop, 1/8 mobile clients support transition fully.
Unsupported in Gmail, Gmail Android, Gmail iOS, Outlook 365 and 6 more.
Partial in Yahoo Mail, Yahoo Mail Android, Yahoo Mail iOS, Samsung Mail and 3 more, behavior differs from browsers, test before relying on it.
Outlook Classic (Word engine, supported to at least 2029) does not fully support transition, and its replacement changes little here; see the deprecation diff.
Documented before/after fixes on this page cover 21 clients, including Gmail and Gmail Android.
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 Mar 29, 2024, synced by Emailens Sep 2, 2026.

Client Support

Client	Category	Engine	Support
Gmail	webmail	Gmail Web	Unsupported
Gmail Android	mobile	Gmail Mobile	Unsupported
Gmail iOS	mobile	Gmail Mobile	Unsupported
Outlook 365	webmail	Outlook Web	Unsupported
Outlook (New)	desktop	Outlook Web	Unsupported
Outlook Classic	desktop	Microsoft Word	Unsupported
Outlook iOS	mobile	Outlook Mobile	Unsupported
Outlook Android	mobile	Outlook Mobile	Unsupported
Outlook for Mac	desktop	WebKit	Unsupported
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	Partial^{See caveat 2}
Thunderbird	desktop	Gecko	Supported
HEY Mail	webmail	WebKit	Partial^{See caveat 3}
Proton Mail	webmail	Proton	Unsupported
AOL Mail	webmail	AOL	Partial^{See caveat 1}
Fastmail	webmail	Fastmail	Supported^{See caveat 4}
Superhuman	desktop	Blink	Partial^{See caveat 5}

Documented caveats (5)

1.Yahoo Mail, Yahoo Mail Android, Yahoo Mail iOS, AOL Mail: Partial. Longhand properties are not supported. Buggy. The all keyword is not supported.
2.Samsung Mail: Partial. Not supported with Outlook accounts.
3.HEY Mail: Buggy. transition-duration is forced to 0 on a global reset style.
4.Fastmail: Transition properties are supported but pseudo-classes like :hover are not.
5.Superhuman: Partial. Blink runs transitions, but the user's reduced-motion setting may disable them.

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

Client-by-client behaviour for transition

Fully supports transition (4): Apple Mail, Apple Mail iOS, Thunderbird, Fastmail.

Partial support (7): Yahoo Mail, Yahoo Mail Android, Yahoo Mail iOS, Samsung Mail, HEY Mail, AOL Mail, Superhuman. Expect rendering quirks unique to each engine. Partial support typically means a subset of values, an ignored shorthand, or sanitizer-specific rewrites.

No support (10): Gmail, Gmail Android, Gmail iOS, Outlook 365, Outlook (New), Outlook Classic, Outlook iOS, Outlook Android, Outlook for Mac, Proton Mail. Plan fallbacks for these clients before relying on transition in production sends.

Fixes & Workarounds

Gmail

Unsupported

CSS transitions are not supported in email.

Before (Broken)

before.html

7 lines

.button {
  background-color: #6d28d9;
  transition: background-color 0.2s;
}
.button:hover {
  background-color: #5b21b6;
}

After (Fixed)

fixed.html

8 lines

.button {
  /* Use the most visually appealing state as default.
     :hover is only supported in a few clients. */
  background-color: #6d28d9;
  color: #ffffff;
  text-decoration: none;
  font-weight: bold;
}

Transitions don't work in email; style the default state well

Gmail Android

Unsupported

CSS transitions are not supported in email.

Before (Broken)

before.html

7 lines

.button {
  background-color: #6d28d9;
  transition: background-color 0.2s;
}
.button:hover {
  background-color: #5b21b6;
}

After (Fixed)

fixed.html

8 lines

.button {
  /* Use the most visually appealing state as default.
     :hover is only supported in a few clients. */
  background-color: #6d28d9;
  color: #ffffff;
  text-decoration: none;
  font-weight: bold;
}

Transitions don't work in email; style the default state well

Gmail iOS

Unsupported

CSS transitions are not supported in email.

Before (Broken)

before.html

7 lines

.button {
  background-color: #6d28d9;
  transition: background-color 0.2s;
}
.button:hover {
  background-color: #5b21b6;
}

After (Fixed)

fixed.html

8 lines

.button {
  /* Use the most visually appealing state as default.
     :hover is only supported in a few clients. */
  background-color: #6d28d9;
  color: #ffffff;
  text-decoration: none;
  font-weight: bold;
}

Transitions don't work in email; style the default state well

Outlook 365

Unsupported

CSS transitions are not supported in email.

Before (Broken)

before.html

7 lines

.button {
  background-color: #6d28d9;
  transition: background-color 0.2s;
}
.button:hover {
  background-color: #5b21b6;
}

After (Fixed)

fixed.html

8 lines

.button {
  /* Use the most visually appealing state as default.
     :hover is only supported in a few clients. */
  background-color: #6d28d9;
  color: #ffffff;
  text-decoration: none;
  font-weight: bold;
}

Transitions don't work in email; style the default state well

Outlook (New)

Unsupported

CSS transitions are not supported in email.

Before (Broken)

before.html

7 lines

.button {
  background-color: #6d28d9;
  transition: background-color 0.2s;
}
.button:hover {
  background-color: #5b21b6;
}

After (Fixed)

fixed.html

8 lines

.button {
  /* Use the most visually appealing state as default.
     :hover is only supported in a few clients. */
  background-color: #6d28d9;
  color: #ffffff;
  text-decoration: none;
  font-weight: bold;
}

Transitions don't work in email; style the default state well

Outlook Classic

Unsupported

CSS transitions are not supported in email.

Before (Broken)

before.html

7 lines

.button {
  background-color: #6d28d9;
  transition: background-color 0.2s;
}
.button:hover {
  background-color: #5b21b6;
}

After (Fixed)

fixed.html

8 lines

.button {
  /* Use the most visually appealing state as default.
     :hover is only supported in a few clients. */
  background-color: #6d28d9;
  color: #ffffff;
  text-decoration: none;
  font-weight: bold;
}

Transitions don't work in email; style the default state well

Outlook iOS

Unsupported

CSS transitions are not supported in email.

Before (Broken)

before.html

7 lines

.button {
  background-color: #6d28d9;
  transition: background-color 0.2s;
}
.button:hover {
  background-color: #5b21b6;
}

After (Fixed)

fixed.html

8 lines

.button {
  /* Use the most visually appealing state as default.
     :hover is only supported in a few clients. */
  background-color: #6d28d9;
  color: #ffffff;
  text-decoration: none;
  font-weight: bold;
}

Transitions don't work in email; style the default state well

Outlook Android

Unsupported

CSS transitions are not supported in email.

Before (Broken)

before.html

7 lines

.button {
  background-color: #6d28d9;
  transition: background-color 0.2s;
}
.button:hover {
  background-color: #5b21b6;
}

After (Fixed)

fixed.html

8 lines

.button {
  /* Use the most visually appealing state as default.
     :hover is only supported in a few clients. */
  background-color: #6d28d9;
  color: #ffffff;
  text-decoration: none;
  font-weight: bold;
}

Transitions don't work in email; style the default state well

Outlook for Mac

Unsupported

CSS transitions are not supported in email.

Before (Broken)

before.html

7 lines

.button {
  background-color: #6d28d9;
  transition: background-color 0.2s;
}
.button:hover {
  background-color: #5b21b6;
}

After (Fixed)

fixed.html

8 lines

.button {
  /* Use the most visually appealing state as default.
     :hover is only supported in a few clients. */
  background-color: #6d28d9;
  color: #ffffff;
  text-decoration: none;
  font-weight: bold;
}

Transitions don't work in email; style the default state well

Proton Mail

Unsupported

CSS transitions are not supported in email.

Before (Broken)

before.html

7 lines

.button {
  background-color: #6d28d9;
  transition: background-color 0.2s;
}
.button:hover {
  background-color: #5b21b6;
}

After (Fixed)

fixed.html

8 lines

.button {
  /* Use the most visually appealing state as default.
     :hover is only supported in a few clients. */
  background-color: #6d28d9;
  color: #ffffff;
  text-decoration: none;
  font-weight: bold;
}

Transitions don't work in email; style the default state well

Yahoo Mail

Partial

CSS transitions are not supported in email.

Before (Broken)

before.html

7 lines

.button {
  background-color: #6d28d9;
  transition: background-color 0.2s;
}
.button:hover {
  background-color: #5b21b6;
}

After (Fixed)

fixed.html

8 lines

.button {
  /* Use the most visually appealing state as default.
     :hover is only supported in a few clients. */
  background-color: #6d28d9;
  color: #ffffff;
  text-decoration: none;
  font-weight: bold;
}

Transitions don't work in email; style the default state well

Yahoo Mail Android

Partial

CSS transitions are not supported in email.

Before (Broken)

before.html

7 lines

.button {
  background-color: #6d28d9;
  transition: background-color 0.2s;
}
.button:hover {
  background-color: #5b21b6;
}

After (Fixed)

fixed.html

8 lines

.button {
  /* Use the most visually appealing state as default.
     :hover is only supported in a few clients. */
  background-color: #6d28d9;
  color: #ffffff;
  text-decoration: none;
  font-weight: bold;
}

Transitions don't work in email; style the default state well

Yahoo Mail iOS

Partial

CSS transitions are not supported in email.

Before (Broken)

before.html

7 lines

.button {
  background-color: #6d28d9;
  transition: background-color 0.2s;
}
.button:hover {
  background-color: #5b21b6;
}

After (Fixed)

fixed.html

8 lines

.button {
  /* Use the most visually appealing state as default.
     :hover is only supported in a few clients. */
  background-color: #6d28d9;
  color: #ffffff;
  text-decoration: none;
  font-weight: bold;
}

Transitions don't work in email; style the default state well

Samsung Mail

Partial

CSS transitions are not supported in email.

Before (Broken)

before.html

7 lines

.button {
  background-color: #6d28d9;
  transition: background-color 0.2s;
}
.button:hover {
  background-color: #5b21b6;
}

After (Fixed)

fixed.html

8 lines

.button {
  /* Use the most visually appealing state as default.
     :hover is only supported in a few clients. */
  background-color: #6d28d9;
  color: #ffffff;
  text-decoration: none;
  font-weight: bold;
}

Transitions don't work in email; style the default state well

HEY Mail

Partial

CSS transitions are not supported in email.

Before (Broken)

before.html

7 lines

.button {
  background-color: #6d28d9;
  transition: background-color 0.2s;
}
.button:hover {
  background-color: #5b21b6;
}

After (Fixed)

fixed.html

8 lines

.button {
  /* Use the most visually appealing state as default.
     :hover is only supported in a few clients. */
  background-color: #6d28d9;
  color: #ffffff;
  text-decoration: none;
  font-weight: bold;
}

Transitions don't work in email; style the default state well

AOL Mail

Partial

CSS transitions are not supported in email.

Before (Broken)

before.html

7 lines

.button {
  background-color: #6d28d9;
  transition: background-color 0.2s;
}
.button:hover {
  background-color: #5b21b6;
}

After (Fixed)

fixed.html

8 lines

.button {
  /* Use the most visually appealing state as default.
     :hover is only supported in a few clients. */
  background-color: #6d28d9;
  color: #ffffff;
  text-decoration: none;
  font-weight: bold;
}

Transitions don't work in email; style the default state well

Superhuman

Partial

CSS transitions are not supported in email.

Before (Broken)

before.html

7 lines

.button {
  background-color: #6d28d9;
  transition: background-color 0.2s;
}
.button:hover {
  background-color: #5b21b6;
}

After (Fixed)

fixed.html

8 lines

.button {
  /* Use the most visually appealing state as default.
     :hover is only supported in a few clients. */
  background-color: #6d28d9;
  color: #ffffff;
  text-decoration: none;
  font-weight: bold;
}

Transitions don't work in email; style the default state well

Production guidance for transition

transition is a CSS property. Across the email client matrix, 4 of 21 tracked clients support it fully, 7 only partially, and 10 not at all. The clients most likely to require a workaround for this feature are Gmail, Gmail Android, Gmail iOS. Each of them needs a tailored fallback. See the per-client examples above for the specific code fix Emailens recommends.

When in doubt, ship a baseline that renders without transition and treat it as progressive enhancement on clients where support is verified. Emailens automatically detects cross-client divergence on this feature when you preview an email, so you can see exactly which template paths break before a campaign goes out.

Related Features

!important accent-color align-items animation aspect-ratio backdrop-filter background background-blend-mode

Check your own HTML for transition

Paste your own, or run the sample below. Analyzed in this page, with no signup and nothing stored.

Zero-Friction Engine Preview

Test your transition layout across 21 email clients

Preview rendering, catch CSS issues, and see how transition displays across Outlook, Gmail, and Apple Mail. Free, no account needed.

Instant live preview · No signup required · 21 email engines

Last tested upstream: Mar 29, 2024 · Last synced by Emailens: Sep 2, 2026

caniemail.com (MIT) records Mar 29, 2024 as the last time transition 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.