Exchange 2016 / Non hybrid environment & MS Graph

Question

I´m trying to get data from On-Prem Exchange Server (2016, with latest version) using MS Graph API in a non-hybrid environment. I´ve registered the application in Azure AD, using application permissions and granted the admin consent already. After performing a http get operation it will give the following error:

Error authenticating with resource

After some research throughout the web I´ve found this article https://www.signorellidenis.com/en/graph-authenticationerror-trying-to-get-the-exchange-server-on-premises/

It seems that on Exchange side there is a missing authentication provider, so that all requests aren´t even forwarded from MS Graph to Exchange.

My questions are:

• Does it work to perform requests to Exchange via MS Graph in a non-hybrid environment? There are no information in the official documentation about this issue.
• Does it work without an authentication provider? Is there another way to perform requests in the environment? Or is the hybrid authentication necessary to do this?

Thank you very much in advance for any hints on this issue!

Answer 1

Just get a confirmation from Microsoft Support that It's not supported to make requests to pure on-premise Exchange 2016 via MS Graph.

MS Graph is designed for O365 cloud data. There is no permission to access on-premise resources.

In a hybrid environment, we can say that we use MS Graph as the interface to require the data. But it still most likely uses EWS to request data from on-premise.

The only way to access data from on-prem Exchange 2016 currently is hybrid deployments. See this document.