Retrieve user’s mailbox items from Exchange Server 2019 On-Prem using Windows Authentication only (Direct from React or through .NET API)

Question

Exchange Server 2019:

The requirement is to enable the user to open a webpage (mainly React JS) which will retrieve and display mailbox items for the current logged-in user by calling the /EWS/Exchange.asmx or any other service in Exchange Server 2019 On-Premises environment (not cloud-based).

Key Points:

1- Connectivity: The client machines, backend servers (including MS Exchange Server), and the domain controller are all on the same network and domain, within an on-premises environment. (not cloud-based)

2- Client: the user will log in to his/her windows machine (which is a domain joined machine) then the user will open the webpage from the browser, then the webpage will do one of the following approaches (Kindy check the diagrams):

a. call the Exchange service directly by leveraging the profile of the logged-in user and display the inbox items, or

b. call a windows-authenticated backend .Net API, the API will pick up the requester user’s profile then will call the Exchange service, and retrieve back the service response to the webpage

3- Authentication: Inbox items retrieval should be using Integrated Windows Authentication (IWA) (not by providing or storing any username / password) while invoking the service 4- Deployment: If the backend .NET API approach is used (Apprach-2), the API will be deployed on a separate web server running IIS.

Note: I have tried lot of POCs and approaches, IWA didn't work with me at all

Diagrams:

Approach 1 : Webpage will call exchange service directly Approach-1 diagram

Approach 2 : Webpage will call .Net API, which will call exchange service Approach-2 diagram