This is a use case for the Robot Manager and Pega Case Management, however there are other ways. Since Pega Robotics by itself provides no infrastructure (i.e. no database or server you can use), you will need to provide that portion. Rather than email, you might use a network share where you save a file from the user's machine and have your RPA process monitor that folder and take action when new files are created (or periodically examine the folder and process the contents). These are just general ideas though. I would suggest you work with your account representative to get some services support as they can provide you the best solution after considering your specific use case and requirements.
I have one query, The application from which i need to get data is not a Pega Application. You have mentioned, We need to use Robot Manager and PEGA Case Management ? I did not use Robot manager earlier. Can you please clarify.
Pega Robot Manager (PRM) was specifically designed to handle providing work to RPA bots running on machines other than the ones a user is working on. Case Management would be required if you didn't want to use Pega Robotics to create the cases on their local machines. PRM triggers work for the RPA process on the creation of a case (or other triggers in a full case flow). If you are not already a Pega Platform user, then that would be a more longer term solution as it requires some planning and setup.