393 votes21 comments · Feature Requests and Feedback » Microsoft Graph/O365 REST APIs · Flag idea as inappropriate… · Admin →
This feature is currently being tested in private beta. Please reach out to email@example.com if you are interested in reviewing and providing feedback!Anonymous supported this idea ·Anonymous commented
Looks like it's still only in beta and undocumented, but it seems to work (if you're willing to risk querying the beta API from your production app).
Syntax: GET /me/messages/ID/$value
The only limitation (that I can tell) is that it's limited to returning a single message per query. You cannot select/filter to retrieve raw rfc822 messages in bulk. I assume there are performance limitations due to the architecture of the underlying data and API. i.e. It may be difficult to port a client, like Thunderbird, to fully sync all raw messages using Graph instead of IMAP.