Using older versions of Outlook for Mac in business environments
I have 365 but i think I might be using the Outlook app, not the web version - I am not technically advanced. But I have solved this problem for me at least. When I go to the View Tab then choose View Settings then Other Settings then choose "Use compact layer widths ..." "smaller than 100 characters", all the headings i want can be included. Hope this helps your situation.