Gmail API returns 403 error code and “Delegation denied for ”

Question

Gmail API fails for one domain when retrieving messages with this error:

com.google.api.client.googleapis.json.GoogleJsonResponseException: 403 OK
{
  \"code         


        

Answer 1

Recently I started exploring Gmail API and I am following the same approach as Guo mentioned. However, it is going to take of time and too many calls when we the number of users or more. After domain wide delegation my expectation was admin id will be able to access the delegated inboxes, but seems like we need to create service for each user.