Yeah, i also have seen the same problem .... when you enable Registration to be "Verified", the [weak] verification code is emailed to users which they use at first-time login. But once you 'unauthorize' them, the Login page simply asks them the "Verification Code" which they already have in email and they get authorized again.

At forum levels, you can ban them by 'expiring' their Role "Registered Members" if your forums are accessible to registered members ONLY. Other than that, i don't know any way to ban accounts.

I think this 'Unauthorize' feature is not good enough, and the Verification Code is sequential like "[portal_id]-[userID]" ... i don't like these weaknesses in DNN ... i hope they fix it.

@ Sebastian

If you'd change the email then they can re-use that email for next registration.

I mean if we have configured for 'unique' emails at registration time, and if someone registered with "john@xyz.com" who was then banned according to your method by changing email to, say, "john_324234@xyz.com" or whatever. His old email "john@xyz.com" can always be used to re-register. The additional step of creating new email account is void then.

Other way around for this would be to create dummy accounts and assign "john@xyz.com" to those, but that would be a pain. If some black-list emails feature is added, that would be better.