I think the Web Administrator could arrange for users of Dawn's IP address to be banned from accessing this website. I also think such censorship might not be that healthy a thing unless a law is broken by a particular post (please, I'm not looking for a debate on this!).
The very best thing that we can do ourselves is to not rise to the bait by replying (kindly, rudely or in any way at all!) or even referring in any way to Dawn or her unkind posts. Responses just feed her habit and she would mistake them for validation.
Best Wishes to All.