How many email clients support text-shadow?

It works in 12 of 21, not supported in 9.

Does text-shadow work in Yahoo Mail iOS?

text-shadow works in Yahoo Mail iOS. Closest to Yahoo Mail: Yahoo Mail iOS, which agrees on 282 of the 298 features both are tested on.

text-shadow in Yahoo Mail

Not supported text-shadow is not supported in Yahoo Mail.

Works in 12 of 21 · not supported in 9

Which clients

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

Your reader in Yahoo Mail sees the email without text-shadow, even if it looks right where you tested it.

The fix for Yahoo Mail

Use font-weight or border-bottom as alternatives to text-shadow

after

6 lines

.glow {
  /* text-shadow is not supported in Gmail, Outlook, Yahoo.
     Use font-weight or letter-spacing for emphasis instead. */
  font-weight: bold;
  letter-spacing: 0.5px;
}

Show the original

before

3 lines

.glow {
  text-shadow: 0 0 10px rgba(255, 255, 255, 0.5);
}

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What Yahoo Mail does with text-shadow

The Emailens probe for text-shadow on a real install counted as Yahoo Mail, captured 14 Oct 2026. It shows the problem, not the fix. Where text-shadow is supported it shows: text with a red shadow.

The Emailens probe for text-shadow on a real Yahoo Mail — Yahoo Mail

The same probe in the Emailens live preview of Yahoo Mail — Yahoo Mail

@emailens/engine 0.18.22 on the original code

Yahoo Mail does not support "text-shadow". Observed 2026-11-08 (Emailens probe sheets 20-22, Yahoo Mail web (Chrome), our own seed inbox): A green text-shadow did not draw; the text rendered plain.

caniemail record, tested upstream 28 Feb 2019

Observed 2026-11-08 (Emailens probe sheets 20-22, Yahoo Mail web (Chrome), our own seed inbox): A green text-shadow did not draw; the text rendered plain.

Your next question

Every feature in Yahoo Mail · text-shadow in every client

Questions

How many email clients support text-shadow?: It works in 12 of 21, not supported in 9.
What do I use instead of text-shadow in Yahoo Mail?: Use font-weight or border-bottom as alternatives to text-shadow.
Does text-shadow work in Yahoo Mail iOS?: text-shadow works in Yahoo Mail iOS. Closest to Yahoo Mail: Yahoo Mail iOS, which agrees on 282 of the 298 features both are tested on.

To see what else in your email Yahoo Mail does not support, paste the whole email.

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Real captures 14 Oct 2026 on 11 installs · caniemail (MIT) via @emailens/engine 0.18.22 · tested upstream 28 Feb 2019 · data last changed 10 Nov 2026 · Outlook (New) cells are the engine's mapping