How to get the user email address inside the bot ?

We need help in understanding how to achieve the following bot workflow.

Workflow:
We need to hit the api which will return user specific data. This API needs user email as a parameter. We will then save the response in variable and use it ahead in the flow.

The Problem:
How to get the user email address without prompting user to enter it.As the user is already authenticated.Does there exist a way to get that authenticated user's information (mainly email) ?. We do not want the user to be prompted for email for the following reasons
1> The user when it came to the bot flow was already authenticated.
2> The user may enter a random email ID. if they are asked for it.

As this is a business critical component. We look forward to hearing from you soon.