I am working with the new ASP.NET Identity (RTM) and I was wondering how would I go on about changing registering and login from being a UserName to an Email.
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As you will have probably found out (and was to be expected), ASP.NET Identity 2.0.0, released March 2014, adds this functionality in the framework.
Announcement: http://blogs.msdn.com/b/webdev/archive/2014/03/20/test-announcing-rtm-of-asp-net-identity-2-0-0.aspx
Full example and tutorial, including account confirmation: http://www.asp.net/identity/overview/features-api/account-confirmation-and-password-recovery-with-aspnet-identity