I have contacted MS O365 support who points at you folks needs to fix your program. The Exchange services aren't missing anything. This issue happened on 2/25 when MS updated O365 on desktops causing Outlook to somehow block your access, but MS wants you folks to then keep up as MS will keep moving forward with developments of this sort. 

the machines are running Windows 10 Pro v1909. The QuickBooks emailing to Outlook works just find when the desktop O365 is still version 1908 Build 11929.20606 but as soon as we install O365 version 2002 build 12527.20194 the connection between QuickBooks desktop and Outlook is broken; so I wonder what have changed and what could be affecting this? ..   who will work on a fix; Microsoft or Intuit QuickBooks?

Meanwhile I have asked MS O365 support how to uninstall the latest version and go back to the version that still works with QuickBooks. 

Your team should test the new Outlook desktop client and let me know what you find - likely that it no longer works with QuickBooks desktop emailing.