How many email clients support border-spacing?

It works in 17 of 21, not supported in Outlook Classic and Outlook for Mac, 2 untested.

Does border-spacing work in Outlook 365?

border-spacing works in Outlook 365. Outlook (New) and Outlook 365 differ on 1 feature: text-shadow.

border-spacing in Outlook (New)

Works border-spacing works in Outlook (New).

Works in 17 of 21 · not supported in 2 · 2 untested

Which clients

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

The fix for the clients that need it

Needed in 2 of 21: Outlook Classic and Outlook for Mac.

Use the cellspacing HTML attribute instead of border-spacing CSS

instead

3 lines

<table cellspacing="8" style="border-collapse: separate;">
  <tr><td>Cell</td></tr>
</table>

Show the original

before

3 lines

<table style="border-spacing: 8px; border-collapse: separate;">
  <tr><td>Cell</td></tr>
</table>

A free account opens all 21 clients and keeps your checks for 7 days. Create a free account →

Your next question

Every feature in Outlook (New) · border-spacing in every client

Questions

How many email clients support border-spacing?: It works in 17 of 21, not supported in Outlook Classic and Outlook for Mac, 2 untested.
Does border-spacing work in Outlook 365?: border-spacing works in Outlook 365. Outlook (New) and Outlook 365 differ on 1 feature: text-shadow.

To see what in your email Outlook (New) does not support, paste the whole email.

Check your email, free

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 10 installs · caniemail (MIT) via @emailens/engine 0.18.22 · tested upstream 20 Dec 2023 · data last changed 10 Nov 2026 · Outlook (New) cells are the engine's mapping