display:flex in Outlook Classic
Not supported display:flex is not supported in Outlook Classic.
Works in 18 of 21 · partial in 2 · not supported in 1
Which clients
- Works
- Gmail, 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, Thunderbird, HEY Mail, Proton Mail, AOL Mail, Fastmail, Superhuman
- Partial
- Gmail Android, Gmail iOS
- Not supported
- Outlook Classic
Your reader in Outlook Classic sees the email without display:flex, even if it looks right where you tested it.
The fix for Outlook Classic
Use table layout as fallback for flexbox in Outlook
<!--[if mso]>
<table role="presentation" width="100%" cellpadding="0"
cellspacing="0" border="0"><tr>
<td width="50%" valign="top">Column 1</td>
<td width="50%" valign="top">Column 2</td>
</tr></table>
<![endif]-->
<!--[if !mso]><! -->
<div style="display: flex; gap: 16px;">
<div style="flex: 1;">Column 1</div>
<div style="flex: 1;">Column 2</div>
</div>
<!-- <![endif]-->Show the original
<div style="display: flex; gap: 16px;">
<div style="flex: 1;">Column 1</div>
<div style="flex: 1;">Column 2</div>
</div>The checker needs a computer screen.
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What Outlook Classic does with display:flex
The Emailens probe for display:flex on 3 real installs counted as Outlook Classic, captured 14 Oct 2026. It shows the problem, not the fix. Where display:flex is supported it shows: three boxes in a row.
caniemail: display:flex is not supported in Outlook Classic.
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@emailens/engine 0.18.22 on the original code
Outlook Classic receives this flex box. The MSO branch needs a table.
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: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 visibility work in Outlook Classic?
Works in 13 of 21 · not supported in 8
fix - Does text-shadow work in Outlook Classic?
Works in 12 of 21 · not supported in 9
fix
Every feature in Outlook Classic · display:flex in every client
Questions
- How many email clients support display:flex?
- It works in 18 of 21, partial in 2, not supported in Outlook Classic.
- What do I use instead of display:flex in Outlook Classic?
- Use table layout as fallback for flexbox in Outlook.
- Does display:flex work in AOL Mail?
- display:flex works 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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The checker needs a computer screen.
Real captures 14 Oct 2026 on 11 installs · caniemail (MIT) via @emailens/engine 0.18.22 · tested upstream 2 Nov 2021 · data last changed 10 Nov 2026 · Outlook (New) cells are the engine's mapping