Forum Discussion
401 Unauthorized when accessing /messages api using client credentials grant flow
I have a mailbox in on prem exchange server (which is in hybrid mode) abc@onprem.com and i am trying to access this via graph api (/messages). This works perfectly if i do this in graph explorer, but...
Karthik_Hebbar I have found the resolution, please see following blog post if it helps: https://blog.thenetw.org/2019/05/13/using-client_credentials-with-microsoft-graph-in-hybrid-exchange-setup/