Using New Outlook on Windows for personal email, calendar, and contact management
I posted this before as my fix but I don't even see it in the thread. I realized you can paste underscores and it would not activate the italics.
I made an autohoykey script to paste and underscore when I hit the hotkey "Shift + minus". If you have other applications that use "Shift + minus", you can make the pasting underscore with something else. Only downside is replacing clipboard with an underscore. (I think most every dev knows autohotkey)
+-::
clipboard := "_"
Send ^v
return