The contents of the reading pane is very narrow if there are images to display. it only takes up the middle third of the pane. There does not seem to be a way of altering it except the using Zoom. The zoom says it is at 100% I have to change it to 300% to get the contents to fill the pane. This only on a per email basis.
If there are no images the contents fill the pane.
I am using Office 365 on Windows 10 64 bit.
Is there a setting that I can alter?