Hello Ravindra B
In reviewing unanswered posts, I encountered your post. I see that you requested assistance quickly and that can often lead to disappointment as the community of forum users are fellow customers and often are unable to respond quickly to customers facing urgent issues.
Were you able to discover a workaround for the issue encountered? I have never extracted email id's or a custom variable from GA although I use it frequently for analysis of data from the Tableau Community Forums.