ResourceNotFound when request the messages in the mail box

Question

I have corporate account that I logged in to Graph Explorer. When I try to fetch my profile, or manager details, it works. When I click in on "my mail", I get the following error:

{
    "error": {
        "code": "ResourceNotFound",
        "message": "Resource could not be discovered.",
        "innerError": {
            "request-id": "f838caba-d769-4873-b7ba-80fd8e7016e4",
            "date": "2017-12-19T21:04:30"
        }
    }
}

If I switch to my private @outlook.com account everything works as it should. What could be the problem in this case ?

Answer 1

You're receiving this error because the mailbox you're attempting to access is located on a local Exchange Server and isn't accessible to Microsoft Graph.

On-prem Exchange Servers are not supported by Microsoft Graph at this time. There is however a preview/beta available for Hybrid Deployments where you have a mix of Exchange On-Prem and Exchange Online mailboxes:

Use REST APIs to access mailboxes in Exchange hybrid deployments (preview)