hello @SteveTin,
Welcome to UiPath Forum good to see you here,
From my understanding of your problem,
You need to * Allow UiPath outlook activity by using the steps:-
Open Outlook as Administrator (right click on the Outlook application → Run as Administrator)
I would love to know more about your problem.
can you try to close your outlook application in you main computer or by using kill process activity with process name property as “outlook”.
I suggest you use another version of outlook if you want to use two outlook applications like outlook 2016.
or you could use for example mailontor mail for test purposes.