Actually curious, so if I understand you correctly what you are saying is that a receiver had some software generated an address like [email protected] and then sent it to the sender for use, that would require email providers cooperation. I am not clear on the "cooperation" parts work. I THINK its basically that email providers block emails based on other criteria like DNSBL. And the "cooperation" bit is to get the providers to manage these cryptographic email addresses like guard against their possible misuse?