Most software applications require users to enter an email or choose a username while registering into the application. In this process, it is critical that the email or username used for registration is a unique one. A primitive way of ensuring that the constraint is met is to check into the database whether the email/username already exists or not. However, this simple process consumes time and processing resources when the number of users grow exponentially. In this project, space efficient probabilistic data structure called Bloom Filter is used to detect duplicate email during registration for a dummy email application. With the use of Bloom Filter membership query does not depend on the size of the set and even if the user size increases exponentially membership query is fast and inexpensive.