Unable to add users : Email address already exists

Unable to add users : Email address already exists

When adding an user if  you get the error email address already exists, please goto Setup-->Users and Permissions-->Requesters and us the search option to search for the email address as per the screenshot below,

Do the same in technicians page if you don't get a result under requester details page.

If you are still facing the same issue, please drop as an email.