How many email clients support overflow?

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

Does overflow work in AOL Mail?

overflow is partly supported in AOL Mail. Closest to Outlook Classic: AOL Mail, which agrees on 206 of the 298 features both are tested on.

overflow in Outlook Classic

Not supported overflow is not supported in Outlook Classic.

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 Outlook Classic sees the email without overflow, even if it looks right where you tested it.

What to do instead in Outlook Classic

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 Outlook Classic does with overflow

The Emailens probe for overflow on 3 real installs counted as Outlook Classic, 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 Outlook 2019 (Windows) — Outlook Classic

The Emailens probe for overflow on a real Outlook 2016 (Windows) — Outlook Classic

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 →

@emailens/engine 0.18.22 on the original code

Outlook Classic does not support "overflow".

Your next question

Every feature in Outlook Classic · 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 Outlook Classic?: Content will always be visible; design for full content display.
Does overflow work in AOL Mail?: overflow is partly supported in AOL Mail. Closest to Outlook Classic: AOL Mail, which agrees on 206 of the 298 features both are tested on.

To see what else in your email Outlook Classic 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