While true, email accounts can and are deleted or closed. Transient addresses on your own domain are usually the best (so you can nuke them when polluted, hat tip to Apple for pushing blind emails into the mainstream with "Sign in with Apple"), but sending fake bounce backs by sender while binning anything incoming from them is a close second (Gmail and Fastmail both support filtering messages directly to Trash, but no fake bounce back messages; could probably do it with an SMTP proxy, again if you use your own domain).