An API that connects multiple Microsoft services, enabling data access and automation across platforms
Hello Kyle Jeynes, Thanks for reaching out. The api call https://graph.microsoft.com/beta/users/<User EmailAddress>/mailfolders/inbox/messages/<Message-ID>/$Value does not support returning Mime content of messages. I received the same error in my test environment for this api call. You can provide your feedback and suggestion regarding this feature at https://aka.ms/graphfeedback. I was however unable to reproduce the issue using the /users/{id}/messages/{id}/$value as this api call returned mime content. Does the issue occur with a specific message or specific mailbox? Does the account you are using to make Graph Api calls have appropriate permissions to the mailbox? Thanks.