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

Our users had migrated into a domain and their account had aliases attached to it. We needed to default the SendAs address to one of the imported aliases and want a way to automate it. The Gmail API looked like the solution, but our privileged user with roles to make changes to the accounts was not working - we kept seeing the "Delegation denied for " 403 error.

Here is a PHP example of how we were able to list their SendAs settings.

useApplicationDefaultCredentials();  // loads whats in that json service account file.
$client->setScopes(SCOPES); // adds the scopes
$client->setSubject($impersonateUser);  // account authorized to perform operation

$gmailObj  = new Google_Service_Gmail($client);

$res       = $gmailObj->users_settings_sendAs->listUsersSettingsSendAs($userKey);

print_r($res);


?>