How many email clients support background-size?

It works in 17 of 21, partial in 3, not supported in Outlook Classic.

Does background-size work in AOL Mail?

background-size works in AOL Mail. Closest to Outlook Classic: AOL Mail, which agrees on 206 of the 298 features both are tested on.

background-size in Outlook Classic

Not supported background-size is not supported in Outlook Classic.

Works in 17 of 21 · partial in 3 · 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 Android, Yahoo Mail iOS, Samsung Mail, Thunderbird, HEY Mail, Proton Mail, AOL Mail, Fastmail, Superhuman
Partial: Gmail Android, Gmail iOS, Yahoo Mail
Not supported: Outlook Classic

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

What to do instead in Outlook Classic

Outlook ignores background-size; use VML or sized images

instead

15 lines

<td background="bg.jpg" bgcolor="#333333" width="600" height="400" valign="top"
    style="background-color: #333; background-image: url('bg.jpg');
           background-size: cover; background-position: center; background-repeat: no-repeat;">
  <!--[if gte mso 9]>
  <v:rect xmlns:v="urn:schemas-microsoft-com:vml" fill="true"
    stroke="false" style="width:600px; height:400px;">
    <v:fill type="frame" size="100%,100%" src="bg.jpg" color="#333333" />
    <v:textbox inset="0,0,0,0">
  <![endif]-->
  <div>Content</div>
  <!--[if gte mso 9]>
    </v:textbox>
  </v:rect>
  <![endif]-->
</td>

Show the original

before

3 lines

<td style="background: url('bg.jpg') center/cover no-repeat;">
  Content
</td>

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What Outlook Classic does with background-size

caniemail record, tested upstream 28 Feb 2019

Background images size can be used in VML with the size attribute. See VML documentation.

Your next question

Every feature in Outlook Classic · background-size in every client

Questions

How many email clients support background-size?: It works in 17 of 21, partial in 3, not supported in Outlook Classic.
What do I use instead of background-size in Outlook Classic?: Outlook ignores background-size; use VML or sized images.
Does background-size work in AOL Mail?: background-size 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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caniemail (MIT) via @emailens/engine 0.18.22 · tested upstream 28 Feb 2019 · data last changed 10 Nov 2026 · Outlook (New) cells are the engine's mapping