Outlook 07/10/13/16 is using a Microsoft Words engine to render an HTML instead of browser engine like all other email clients do. Since Words doesn’t create for HTML in the first place it’ll lack code support such as a background-image. It’ll show a solid background color instead. That why I made a background image slightly overlay so a user can see when they modify a background color in the builder.

I understand there is a workaround for this, but as I testing it still not reliable randomly breaking a template layout(in Outlook) and require to manually edit directly at the code when changing the image. So I’m not implementing the template code to prevent any further issue and it a workaround not a proper way to coding the template anyway.

I’m also aware, there’s some email developer in the market, advertise a working background image on Outlook. However, none of them is a full-width layout(width=”100%”). It may look like full-width but when you display in a full browser or webversion. It just contains in 800px or any specific container.

by the way, there’s a good news from the recent update of Litmus partnership with Microsoft to improve Outlook rendering. At this moment two most popular Outlook bugs are reported(background images and web fonts). We can expect more update is coming soon from MS. Once they release an update, there will be no need for the workaround or update the template code. Outlook It should automatically support as it is today.

more info at Litmus blog > An Update on the Litmus-Microsoft Partnership