Here we go: Don’t make as read on Outlook for Windows
In our answer, we’ll be covering both Windows and macOS unread settings for Outlook. Now the question is the following: is there a way to modify the read / unread settings to keep my messages marked as unread in Outlook unless i explicitly set them as read (by making a right click and selecting Mark as Read). What’s annoying is that i have noticed that items that i view in the Reading Pane are shown as being read as well… This makes it difficult for me to follow up on my email and take the required action. I have noticed that after i click on a specific email entry in the Outlook Mail tab and open it for reading, it shows as read.
