How do I block a website called domainxchange.com from my imac
I keep getting notifications that my mac has been infected when its not, from the same website domainxchange.com telling me I won a thousand dollars. How do I block this domainxchange.com I tried going to advanced setting and added to blocked sites but I continue to get bombarded with stuff from them.
iMac 27" 5K, macOS 10.13