My site is running DNN 6.1.1 and until recently there has been no need to update as it serves me fine. Over the last month it seems someone has it in for me and is continually registering new users on the site with invalid email addresses. My site is set to verified registration so they are not getting access to registered user functions but it is really annoying to have all these non-delivery emails from my SMTP provider. I have checked the event viewer and all these registrations have a blank IP addresses. I can't block them if I don't know the IP. I suspect I know whom is behind this but the authorities are not interested so it's up to me to try and sort this out.

Does anyone have any suggestions as to how I can combat this?

Right now  site registration is turned off but that's cutting off my nose to spite my face. I suspect the person behind this is using an anonymous proxy as they have harrassed me by other means in the past using this method. Ideally being able to block proxy IP's might help but I don't know how to do this or if it is even possible.

TIA steve