On Mon, 09 Oct 1995 23:12:35 -0400 (EDT), dlv@bwalk.dm.com (Dr. Dimitri Vulis) wrote:
Scenario 3.
Alice provides dial-up Usenet feed to/from several small sites run by Bob, Charles, and Dan. Their domains point to Alice via MX. Alice knows that if one of them spams Usenet, she'll be flamed and mailbombed. Alice adds her own "Cancel-Lock:" to each article she receives from these sites before feeding them to the rest of Usenet. Later she can cancel whatever articles have originated at B, C, D, and passed through her site.
I like this a lot, except: If B doesn't add a Cancel-Lock to each article he sends, he loses the ability (because of Alice's Cancel-Lock) to cancel his own articles. Cancel-Locks should only be added (or honored?) if the message contains a Cancel-Lock from the originator. I'd also like to suggest that added Cancel-Locks be generated from something less than the full message -- perhaps from just the message ID. Intermediate sites are unlikely to maintain full copies of all messages, and ought to be able to generate cancels in response to a (possibly corrupted) copy returned to postmaster from another site.