I tried to subscribe to resource Users/xxx/mailFolders('Inbox')/messages and got error Status Code: NotFound; Reason: REST API is not yet supported for this mailbox. I have found that user has licences attached to file.76244-lic.txt
One of them is EXCHANGE_S_ENTERPRISE. What name of licence should be for success subscribing?
I read that error also can occur if the mailbox is on a dedicated Microsoft Exchange Server and is not a valid Office 365 mailbox. How can I check from graph api if user has valid Office 365 mailbox?