Certainly. Many ISP and telecommunication service providers do have spam filters on their network to try to identify keywords that will block out spam. Obviously the system isn't perfect, and spammers who are deliberately trying to reach you to do nefarious things are quick to act and get around that.
In a similar example, not related to CASL but to spoofing of telephone calls, we put in a fix to eliminate a telephone number that someone has been spoofing. The spammers know and they've moved on to another one. They're quick acting, and we're just keeping pace with them.