Still no way to add a simple email background image that works in Outlook and OWA?

Question

Is it true that it is still not possible to add a simple background image to email that shows up in most mail clients, at least in Outlook.exe and OWA (aka Outlook.com)?

I've tried most of the typical hacks already, including various ones with VML, but none have worked (in Outlook 365 as of 2021).

The only thing that works within Outlook itself is the page background image as known from Microsoft Word:

But of course that doesn't show up in any other mail client, not even OWA.

Answer 1

Outlook uses Word as a rendering engine for message bodies. And Word considers unsupported cascading style sheet properties to be unknown properties:

• background-attachment
• background-image
• background-position
• background-repeat

Instead, you can use embedded images (hidden attachments) in the message bodies by suing the cid attribute in the HTML markup.