Registrations with ridiculous/offensive email addresses

[rondorr]

I do free classes for older adults so I always get registrations from email addresses like this one tonight, "***********".  I'd like to block it before the class starts because we just have to remove these people once the class starts. We block the chat and cameras and take all the security measures, but it's still annoying. I could cancel the ticket, but that doesn't stop them from registering for another one. Do I have to wait until the class starts to remove people so they're blocked and can't get in, or is there a way to reduce these by getting them before the class starts? I'm super frustrated because I'm trying to get to an underserved audience and keep it free, but I don't know how to keep out the riff-raff except to remove them. Again, I've blocked a lot using the security settings recommended in all the tutorials, but they still get through to the host and co-hosts. Thanks! 

[rondorr]

The e-mail address was blocked in my post, so you'll have to trust me, it was offensive.