Background-images aren't loaded in Office365 in Litmus and in my office365 as well. They only show when you click on “To always show content from this sender, click here”.

Because using the same rendering engine I imagine that this could be the case for as well, but I wasn't able to reproduce the same situation in Does anyone know how to change the preferences for downloading images in

I tried background attribute, shorthand and longhand(?) css and it seems that these all get stripped.