googleworkspace#336 use the with_subject method

If you have delegated domain-wide access to the service account and you want to impersonate a user account, use the with_subject method of an existing ServiceAccountCredentials object.

Author: jackred8

gmail/snippet/settings snippets/update_signature.py

@@ -30,7 +30,8 @@ def update_signature():
     for guides on implementing OAuth2 for the application.
     """
     creds, _ = google.auth.default()
-
+    # If you want to use service account to impersonate a user account
+    # creds = creds.with_subject('[email protected]')
     try:
         # create gmail api client
         service = build('gmail', 'v1', credentials=creds)