In case of successfully login, 30 characters session token will be set in response header.
auth_tk : CDSachFszCDwwASu6lLZLbypoYEECM
This session will be valid for 30 mins.
Note* Add subscriber Method can only accept 200 subscribers in single request. First subscriber's elements would be handled as a Update Layout for subscribers against that request.
No XML required. Only need to call request URL.