Logging to a DotNetNuke (DNN) site with either username or email is not supported out of the box. Here is a simple way to do this. First, make sure the membership provider in your Web.config is set to require unique emails when creating accounts. You'll find this on this section of your Web.config: add name="AspNetSqlMembershipProvider" type="System.Web.Security.SqlMembershipProvider" connectionStringName="SiteSqlServer" enablePasswordRetrieval="true" enablePasswordReset="true" requiresQuestionAndAnswer="false"...