There was a hack posted which allows banning of both the proxy server they're using and/or their real IP.
This way they can't keep changing proxies and continue posting because their real IP is banned too.
Unfortunately this mod is for 6.3 (what I'm using) and I have no idea how much work would be needed to convert it to 6.5
https://www.ubbdev.com/forum/showflat...prev=#Post91358 There is *one* way around this but I'm not gonna say how for obvious reasons.
