Hi, DNN by default sets requiresUniqueEmail= false. We went like with this unknowingly now there are duplicate accounts using same email address. Is there any way in dnn to enable this constraint and stop creating duplicate accounts with same email? When I enable the constraint requiresUniqueEmail= true, if a user tries to login, he will be getting the screen saying invalid email. I tried to delete the duplicate accounts, but with dnn 5 it is only soft delete, and when I login with a single final account it still shows invalid email. I tried to message the email of the duplicate accounts in Aspnet_membership and Users table to update to append the username to the email. Now, when I login, I still see the same error. Is there any way in dnn to enable this constraint and stop creating duplicate accounts with same email?

You can change web.config to require unique email addresses.

Chris Hammond has a blog entry here about hard deleting users.  If you do this, I would recommend doing it on a copy of your live database.