Using New Outlook on Windows for personal email, calendar, and contact management
I have not found a solution to this aggravating issue, but I did discover an optional workaround:
Press the CNTRL key and click on the email - it will then check the box and highlight it instead of opening the email. Essentially it works like the old Outlook when using the CNTRL key to select several emails at a time.
Not ideal, but thought I'd share. Sorry in advance if someone shared this already.