visibility in Outlook Classic
Not supported visibility is not supported in Outlook Classic.
Works in 13 of 21 · not supported in 8
Which clients
- Works
- Outlook 365, Outlook (New), Outlook iOS, Outlook for Mac, Apple Mail, Apple Mail iOS, Yahoo Mail iOS, Samsung Mail, Thunderbird, HEY Mail, Proton Mail, Fastmail, Superhuman
- Not supported
- Gmail, Gmail Android, Gmail iOS, Outlook Classic, Outlook Android, Yahoo Mail, Yahoo Mail Android, AOL Mail
Your reader in Outlook Classic sees the email without visibility, even if it looks right where you tested it.
The fix for Outlook Classic
Use conditional comments or remove hidden content
The engine still flags this in the fix: Outlook Classic does not support "max-height".
<!-- For screen readers, use font-size: 0 trick -->
<div style="font-size: 0; max-height: 0; overflow: hidden;
mso-hide: all;" aria-hidden="true">
Preheader text
</div>Show the original
<div style="visibility: hidden;">
Hidden content for screen readers
</div>The checker needs a computer screen.
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What Outlook Classic does with visibility
The Emailens probe for visibility on 3 real installs counted as Outlook Classic, captured 14 Oct 2026. It shows the problem, not the fix. Where visibility is supported it shows: a, gap, b (no hidden word).
caniemail: visibility is not supported in Outlook Classic.
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@emailens/engine 0.18.22 on the original code
Outlook Classic does not support "visibility".
Your next question
- Does word-break work in Outlook Classic?
Works in 4 of 21 · partial in 12 · not supported in 5
fix - Does display:flex work in Outlook Classic?
Works in 18 of 21 · partial in 2 · not supported in 1
fix - Does display:grid work in Outlook Classic?
Works in 18 of 21 · partial in 2 · not supported in 1
fix - Does border-spacing work in Outlook Classic?
Works in 17 of 21 · not supported in 2 · 2 untested
fix - Does border-radius work in Outlook Classic?
Works in 16 of 21 · partial in 4 · not supported in 1
fix - Does text-shadow work in Outlook Classic?
Works in 12 of 21 · not supported in 9
fix
Every feature in Outlook Classic · visibility in every client
Questions
- How many email clients support visibility?
- It works in 13 of 21, not supported in 8.
- What do I use instead of visibility in Outlook Classic?
- Use conditional comments or remove hidden content.
- Does visibility work in AOL Mail?
- visibility is not 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.
No signup · Five clients free, Outlook Classic included · All 21 with an account
The checker needs a computer screen.
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