What you say can be applicable for subscription billing. But there are hundreds of other sites and apps where you can "checkout" stuff without needing to regist

What you say can be applicable for subscription billing. But there are hundreds of other sites and apps where you can "checkout" stuff without needing to register, which is also a welcome/better feature. And yes, they do notify when a transaction failed. You cannot ask a whole ecosystem to change because of a feature/flaw on a central vendor. Where will you start? Force people to create accounts and verify emails when buying a one-off train ticket or ordering a pizza? What if people/market don't want this registration/activation crap for doing small utility stuff? For a payment, I have to authenticate with my payment provider, not to my email vendor. And payment providers do have delayed reconciliation issues that are sometimes notified back. And where would you stop? Validate each and every piece of info the user provides? Send a SMS verification code to the phone for same utility bill? The conclusion is correct: Fix the vendor. I asked for a specific email address when I signed up. Similarly I should get emails only for "dots" that I have specifically opted in to. Deny receiving the email, show me a warning, don't allow it until I opt in. Anything else is just asking for trouble.