How many email clients support position?

It works in 2 of 21, partial in 14, not supported in 5.

Does position work in Apple Mail?

position is partly supported in Apple Mail. Closest to Fastmail: Apple Mail, which agrees on 192 of the 235 features both are tested on.

position in Fastmail

Partial position is partly supported in Fastmail.

Supports relative, absolute but not sticky and fixed.

Works in 2 of 21 · partial in 14 · not supported in 5

Which clients

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

Your reader in Fastmail may not see position the way you wrote it, even if it looks right where you tested it.

What to do instead in Fastmail

Use table-based positioning instead of CSS position

instead

7 lines

<table role="presentation" width="100%" cellpadding="0"
  cellspacing="0" border="0">
  <tr>
    <td valign="top">Content</td>
    <td width="80" valign="top" align="right">Badge</td>
  </tr>
</table>

Show the original

before

6 lines

<div style="position: relative;">
  <div style="position: absolute; top: 0; right: 0;">
    Badge
  </div>
  <p>Content</p>
</div>

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What Fastmail does with position

caniemail record, tested upstream 16 May 2021

Partial. Supports relative, absolute but not sticky and fixed.
Buggy. fixed is replaced by absolute.

Your next question

Every feature in Fastmail · position in every client

Questions

How many email clients support position?: It works in 2 of 21, partial in 14, not supported in 5.
What do I use instead of position in Fastmail?: Use table-based positioning instead of CSS position.
Does position work in Apple Mail?: position is partly supported in Apple Mail. Closest to Fastmail: Apple Mail, which agrees on 192 of the 235 features both are tested on.

To see what else in your email Fastmail does not support, paste the whole email.

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caniemail (MIT) via @emailens/engine 0.18.22 · tested upstream 16 May 2021 · data last changed 10 Nov 2026 · Outlook (New) cells are the engine's mapping