Authenticity of the email sender is extremely important in many cases. Personal digital certificates are generally used for the same. Personal digital certificates need to be signed by a third party trusted CA. In a large organization, it is not very economical to provide individual certificates to each user.
Workout a unique solution to determine the authenticity of the email sender without using such personal digital certificates.

Notes: In order to demonstrate the working of the solution, participants have to simulate an email setup with test user accounts.

Sample Data Required: No