We are using EMAIL Settings API and ClientLogin for Authentication. EMAIL Settings API is still on GDATA Libraries. Using GDATA libraries can we start using OAuth 2.0 ? (we are using the appsforyourdomain client library to use EMAIL Settings API) Or can we continue using ClientLogin ? Based on the post looks like ClientLogin is going to retire by April 20, 2015. Please guide me the right approach. GDATA API : 1.46.0. EMAIL Settings API is used only for disabling the webclips for the user.