title: does authorization code for gmail oauth2 ever expires
body: <p>I am trying to use <strong>gmail smtp</strong> using <strong>oauth 2.0</strong>. I have used <strong>aspose.dll</strong> for requesting access token using authorization url. I do not get refresh token when i get the response.so there is no way to request new access token if previous is expired. So i thought of getting access token every-time my app requires . And if authorization code gets expired then i can not follow this approach.</p>
  
  <p>does authorization code for gmail oauth2 ever expires??</p>