In this tutorial, you will learn how to use Unique Email Address for new user registration in DNN. This unique email address is sometimes useful, especially if you are running an ecommerce website in DNN.
To setup, you basically need to open your web.config file, this file is located under your root folder.
Look for the following word "requiresUniqueEmail" and set the value to true.
<add name="AspNetSqlMembershipProvider" type="System.Web.Security.SqlMembershipProvider" connectionstringname="SiteSqlServer" enablepasswordretrieval="true" enablepasswordreset="true" requiresquestionandanswer="false" minrequiredpasswordlength="7" minrequirednonalphanumericcharacters="0" requiresuniqueemail="true" passwordformat="Encrypted" applicationname="DotNetNuke" description="Stores and retrieves membership data from the local Microsoft SQL Server database"> </add>