CSS property · 10 real installs 14 Oct 2026 · data last changed 10 Nov 2026
border-spacing in email clients
Works in 17 of 21. Not supported in Outlook Classic and Outlook for Mac. Untested in HEY Mail and Fastmail.
Your reader in Outlook Classic sees the email without border-spacing, even if it looks right where you tested it.
caniemail (MIT) via @emailens/engine 0.18.22
The fix for Outlook Classic
Use the cellspacing HTML attribute instead of border-spacing CSS
<table cellspacing="8" style="border-collapse: separate;">
<tr><td>Cell</td></tr>
</table>Show the original
<table style="border-spacing: 8px; border-collapse: separate;">
<tr><td>Cell</td></tr>
</table>The checker needs a computer screen.
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border-spacing on 10 real installs
One Emailens probe, screenshotted on each install on 14 October 2026, next to our live preview of the same client. Where border-spacing is supported you should see: 8px gaps between cells.
caniemail: border-spacing is not supported in Outlook Classic.
caniemail: border-spacing works in Outlook 365.
This Outlook.com install drops the <style> in the head, so only inline styles apply.
caniemail: border-spacing works in Apple Mail.
caniemail: border-spacing works in Apple Mail iOS.
caniemail: border-spacing works in Yahoo Mail.
Also captured, not counted as evidence (3)
- Outlook for Microsoft 365 · not mapped to an engine client yet Real screenshot
- Outlook 2019 for Mac (legacy app) · not counted as Outlook for Mac Real screenshot
This is the legacy Outlook for Mac app. The new Outlook for Mac, which the table describes, drops gradients, grid sizing functions, var() and more.
- Gmail (web) · not counted as Gmail Real screenshot
This Gmail install does not apply Gmail's sanitiser, so it shows more than real Gmail does.
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 →
All 21 clients, problems first
| Client | Support |
|---|---|
| Outlook Classic | Not supported |
| Outlook for Mac | Not supported |
| HEY Mail | Untested |
| Fastmail | Untested |
Works in 17: Gmail, Gmail Android, Gmail iOS and 14 more. Show all
| Client | Support |
|---|---|
| Gmail | Works |
| Gmail Android | Works |
| Gmail iOS | Works |
| Outlook 365 | Works |
| Outlook (New) | Works |
| Outlook iOS | Works |
| Outlook Android | Works |
| Apple Mail | Works |
| Apple Mail iOS | Works |
| Yahoo Mail | Works |
| Yahoo Mail Android | Works |
| Yahoo Mail iOS | Works |
| Samsung Mail | Works |
| Thunderbird | Works |
| Proton Mail | Works |
| AOL Mail | Works |
| Superhuman | Works |
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fix
border-spacing in Outlook Classic · Every feature in Outlook Classic · All email CSS features · What real installs show
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