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CSS property · data last changed 10 Nov 2026

gap in email clients

Works in 7 of 21. Not supported in Outlook Classic, Yahoo Mail, Yahoo Mail Android and 2 more. Partial in Gmail, Gmail Android, Gmail iOS and 6 more.

Your reader in Outlook Classic sees the email without gap, even if it looks right where you tested it.

caniemail (MIT) via @emailens/engine 0.18.22

The fix for Outlook Classic

Use padding or margin on child elements instead of gap

after 
<table role="presentation" cellpadding="0"
  cellspacing="0" border="0">
  <tr>
    <td style="padding-right: 16px;">Item 1</td>
    <td style="padding-right: 16px;">Item 2</td>
    <td>Item 3</td>
  </tr>
</table>
Show the original
before 
<div style="display: flex; gap: 16px;">
  <div>Item 1</div>
  <div>Item 2</div>
  <div>Item 3</div>
</div>

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gap is not among the 24 features we have screenshotted on real installs. The ones we have →

All 21 clients, problems first

ClientSupport
Outlook Classic Not supported
Yahoo Mail Not supported
Yahoo Mail Android Not supported
Yahoo Mail iOS Not supported
AOL Mail Not supported
Gmail Partial See caveat 1
Gmail Android Partial See caveat 1
Gmail iOS Partial See caveat 1
Outlook 365 Partial See caveat 1
Outlook (New) Partial See caveat 1
Outlook iOS Partial See caveat 1
Outlook Android Partial See caveat 1
Outlook for Mac Partial See caveat 1
Fastmail Partial See caveat 2
Works in 7: Apple Mail, Apple Mail iOS, Samsung Mail and 4 more. Show all
ClientSupport
Apple Mail Works
Apple Mail iOS Works
Samsung Mail Works
Thunderbird Works
HEY Mail Works
Proton Mail Works
Superhuman Works

Caveats (2)

  1. 1. Gmail, Gmail Android, Gmail iOS, Outlook 365, Outlook (New), Outlook iOS, Outlook Android, Outlook for Mac: Partial. Supports column-gap for flexbox.
  2. 2. Fastmail: Partial. Supports gap and column-gap for flexbox. Supports gap for multi-column layout (i.e. in conjunction with CSS column-count property)

Caveats as recorded by caniemail (MIT), one entry per wording.

How gap behaves

In Outlook, gap only works as column-gap between flex items: Outlook 365, Outlook (New), Outlook for Mac and the Outlook mobile apps apply that, and Outlook Classic ignores gap entirely. Gmail behaves like the newer Outlooks, Yahoo Mail and AOL Mail ignore gap, and wherever it is dropped the items sit flush against each other.

  • For Gmail, Gmail Android, Gmail iOS, Outlook 365, Outlook (New), Outlook for Mac, Outlook iOS and Outlook Android, the support data lists only column-gap in a flex container. Do not count on row gaps or gaps in a grid there.
  • Full support is limited to Apple Mail, Apple Mail iOS, Samsung Mail, Thunderbird, HEY Mail, Proton Mail and Superhuman. Fastmail supports gap and column-gap in flex containers, and gap with column-count for multi-column text.
  • Proton Mail web lists full support, but when we read delivered messages on November 4, 2026, it removed gap and row-gap from an inline style that also held another property, such as padding. A style holding only gap was left as written.
  • Outlook Classic ignores gap along with display:flex itself, and it applies padding only on table cells, so spacing there has to come from cell padding.

Space items with padding on table cells: padding-right on every cell but the last. Cell padding works in every client, Outlook Classic included. Outlook Classic gives every cell in a row the largest vertical padding in that row, so keep vertical padding equal across a row. If you keep a flex row for other clients, write column-gap rather than gap, since that is the form Gmail and the newer Outlooks apply.

Questions

Does gap work in Outlook?

Partly. Outlook 365, Outlook (New), Outlook for Mac, Outlook iOS and Outlook Android apply column-gap between flex items only. Outlook Classic ignores gap and flex alike, so use padding on table cells there.

Does gap work in Gmail?

Only as column-gap in a flex container, on the web and in the apps. Row gaps and grid gaps are not listed as supported, so space rows with padding instead.

Your next question

gap in Outlook Classic · Every feature in Outlook Classic · All email CSS features · What real installs show

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caniemail (MIT) via @emailens/engine 0.18.22 · tested upstream 28 Dec 2022 · data last changed 10 Nov 2026 · Outlook (New) cells are the engine's mapping