We're using Graph API from office-js addin to send messages. Sometimes the user is sending many attachments and our app is getting throttled. In the response there is a Retry-After header, sometimes for a long time like 3 minutes. The problem is that since our code run in a browser, we can't access the Retry-After header since it is not exposed. The header that should expose it only expose these headers:
ETag, Location, Preference-Applied, Content-Range, request-id, client-request-id, ReadWriteConsistencyToken, SdkVersion, WWW-Authenticate
Retry-After is missing.