One more reason to implement the append-only log using blockchain technology. Seems like a good fit. I don't think privacy laws can be applied to a blockchain, but probably that is still unclear. For example, if I post my email address in a Bitcoin transaction, can I then force every user to delete their blockchain?
You would not be able to stop individual users from doing so, but you could potentially make it legally untenable for commercial/corporate operators.
But personally, regardless of legality, if Google implements this with the degree of disclosure of e-mail details, I'll find another operator that isn't implementing this proposal.
I think you're misunderstanding the gossip protocol, but, regardless, that was not the claim I was responding to, it was that the disclosure of email addresses (or a hash of them) with no way to remove them from the Key Directory is somehow beyond the pale for a public (and automated) key exchange system.
