How to block traffic from qq.com and or mx3.qq.com

My site is getting thousands of bot signups and then we are getting errors when the server sends confirmation emails.

How do I block all incoming traffic from qq.com and/or mx3.qq.com?

I’ve tried creating various WAF rules which don’t seem to help.

It looks like neither of these records is going over Cloudflare

% dig qq.com +short
113.108.81.189
203.205.254.157
123.150.76.218

% dig mx3.qq.com +short
203.205.219.57

Without the record behind the proxy you are only using our DNS services for it.