{ "error": { "code": 401, "message": "API keys are not supported by this API. Expected OAuth2 access token or other authentication credentials that assert a principal. See https://cloud.google.com/docs/authentication", "errors": [ { "message": "Login Required.", "domain": "global", "reason": "required", "location": "Authorization", "locationType": "header" } ], "status": "UNAUTHENTICATED", "details": [ { "@type": "type.googleapis.com/google.rpc.ErrorInfo", "reason": "CREDENTIALS_MISSING", "domain": "googleapis.com", "metadata": { "service": "gmail.googleapis.com", "method": "caribou.api.proto.MailboxService.GetProfile" } } ] } } Invalid email address