When you need to register on a website, you can opt-in into a random email that is generated by Apple. Something like cooker-huskies0u@icloud.com. They then set

When you need to register on a website, you can opt-in into a random email that is generated by Apple. Something like cooker-huskies0u@icloud.com. They then setup a relay that sends everything it receives to your email that is registered with your Apple Id. You can cancel any of those emails whenever and never hear from that website again. There's a similar offering from joint venture of Fastmail and 1Pawword if you're not into Apple.