How many email clients support overflow?

It works in 4 of 21, partial in 16, not supported in Outlook Classic.

Does overflow work in Apple Mail iOS?

overflow is partly supported in Apple Mail iOS. Closest to Apple Mail: Apple Mail iOS, which agrees on 284 of the 298 features both are tested on.

overflow in Apple Mail

Partial overflow is partly supported in Apple Mail.

overflow-block & overflow-inline not supported.

Works in 4 of 21 · partial in 16 · not supported in 1

Which clients

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

Your reader in Apple Mail may not see overflow the way you wrote it, even if it looks right where you tested it.

What to do instead in Apple Mail

Content will always be visible; design for full content display

instead

5 lines

<!-- Show full content, or truncate server-side -->
<div style="max-height: 200px;">
  Shortened content that fits...
  <a href="https://example.com/full">Read more</a>
</div>

Show the original

before

3 lines

<div style="max-height: 200px; overflow: hidden;">
  Long content that gets clipped...
</div>

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What Apple Mail does with overflow

The Emailens probe for overflow on a real install counted as Apple Mail, captured 14 Oct 2026. It shows the problem, not the fix. Where overflow is supported it shows: only one line shows.

The Emailens probe for overflow on a real Apple Mail (macOS) — Apple Mail

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

Every account includes one free real-device check in classic Outlook, Outlook for Mac and Apple Mail, after you verify your email and run one preview, while this month's free capacity lasts. How real-device checks work →

caniemail record, tested upstream 27 May 2025

Partial. overflow-block & overflow-inline not supported.

Your next question

Every feature in Apple Mail · overflow in every client

Questions

How many email clients support overflow?: It works in 4 of 21, partial in 16, not supported in Outlook Classic.
What do I use instead of overflow in Apple Mail?: Content will always be visible; design for full content display.
Does overflow work in Apple Mail iOS?: overflow is partly supported in Apple Mail iOS. Closest to Apple Mail: Apple Mail iOS, which agrees on 284 of the 298 features both are tested on.

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

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Real captures 14 Oct 2026 on 10 installs · caniemail (MIT) via @emailens/engine 0.18.22 · tested upstream 27 May 2025 · data last changed 10 Nov 2026 · Outlook (New) cells are the engine's mapping