How many email clients support transition?

It works in 4 of 21, partial in 7, not supported in 10.

Does transition work in Apple Mail?

transition works in Apple Mail. Closest to Proton Mail: Apple Mail, which agrees on 203 of the 300 features both are tested on.

transition in Proton Mail

Not supported transition is not supported in Proton Mail.

Works in 4 of 21 · partial in 7 · not supported in 10

Which clients

Works: Apple Mail, Apple Mail iOS, Thunderbird, Fastmail
Partial: Yahoo Mail, Yahoo Mail Android, Yahoo Mail iOS, Samsung Mail, HEY Mail, AOL Mail, Superhuman
Not supported: Gmail, Gmail Android, Gmail iOS, Outlook 365, Outlook (New), Outlook Classic, Outlook iOS, Outlook Android, Outlook for Mac, Proton Mail

What to do instead in Proton Mail

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

instead

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;
}

Show the original

before

7 lines

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

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Your next question

Every feature in Proton Mail · transition in every client

Questions

How many email clients support transition?: It works in 4 of 21, partial in 7, not supported in 10.
What do I use instead of transition in Proton Mail?: Transitions don't work in email; style the default state well.
Does transition work in Apple Mail?: transition works in Apple Mail. Closest to Proton Mail: Apple Mail, which agrees on 203 of the 300 features both are tested on.

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caniemail (MIT) via @emailens/engine 0.18.22 · tested upstream 29 Mar 2024 · data last changed 10 Nov 2026 · Outlook (New) cells are the engine's mapping