Ever since I got a new work laptop (Dell Latitude 5480 with terrible screen resolution) with Outlook 2016 on Windows 10 (64-bit), I noticed that all HTML emails with images were showing much smaller than on older versions of Outlook. I notice that Litmus does not provide a test for this configuration in Checklist - perhaps it is a looming headache no one wants to deal with.

There are instances of people complaining about this issue in Microsoft forums but I could find no definitive explanation or solution. I've created and tested bare-bone emails to see if I could isolate the cause: specifying the width inline, specifying the width in CSS, no width specified etc., but to no avail so far.

The images are shrunk exactly by one-third. If you use images to define the width of a table cell, then the table cell will also shrink by one-third.

If anyone has a solution, please do share. I will keep pressing on in my spare time trying to figure yet another Microsoft conundrum.