Written by request for Huwr (see this topic).
If a pending account is denied by the form administrator, the Email address of that account will be automatically inserted into a table of banned addresses. Any future attempt(s) to register using that account will be denied without administrator intervention. Get your copy at SnitzBitz.

Is it possible for the admin to change their minds and then allow the address?

why on earth would you want to do that? the whole point of this is to ban the email address of someone whose registration attempt you have denied, why would you then want to re-allow the email address, that would be pointless, since they were obviously spammers if you deleted them in the first place.

Well, I agree some admin are perfect, sadly I am only attempting to be perfect and its quite possible to deny an account as spam or what ever, only to later find out it wasn't as first seemed.

OK, added the ability for the administrator to manually add/delete any email address.