This site uses an off the shelf/store bought software called vBulletin. While there are a huge number of Tweeks and Twerks on the internet, we don't use any of them here.

And the good news bad news is that vBulletin does have a "Blacklist" function.....but it doesn't do what you're asking about.

vBulletin manages blacklists through built-in options to block unwanted IP addresses, specific email domains, and user accounts.