[23:30:20:701]|[01-23-2023]|[com.adventnet.servicedesk.common.MailUtilities]|[INFO]|[73]: Proxy not enabled for ews. isIncoming: true|
[23:30:21:076]|[01-23-2023]|[SYSERR]|[INFO]|[73]: microsoft.exchange.webservices.data.core.exception.service.remote.ServiceRequestException: The request failed. The request failed. The remote server returned an error: (401)|

Possible root cause: 

The user might add the app registration under different tenants verify the same with the user. Check the domain names in the Azure portal login screen.

Solution:

Changing the tenant to multitenant or login to Azure using the email tenant used on the mail server settings.