I handle spam by handing a unique email address to every entity that requests my address (domain wildcard). What would be better is if there was an initial "hel

I handle spam by handing a unique email address to every entity that requests my address (domain wildcard). What would be better is if there was an initial "hello" where some entity requested permission to send me email, and I could approve, deny, or even revoke in the future. Basically, the issue is that senders cannot be reliably identified. If this were fixed, then spam filtering would be trivial.