Hi Rohit,
There's a REST API for Office 365. Here's the link to the details for Outlook:
https://docs.microsoft.com/en-us/previous-versions/office/office-365-ap…
Is the client not willing to use the Outlook VBO in Blue Prism 6.3? (this is also assuming that MAPIEx doesn't work well for you too)
Respectfully,
Dave