Hm... let me try this (with apologies for apparent abuse and delay) >> Actually we need to validate two assertions: >> >> * That the mail came from the stated author, e.g. PHB. >> * That the mail was relayed by the IETF mailing list. > > Well, yes, but those are easy. Are they? If you can read this, then the first bullet was not applied, however easy doing so would have been. > What's hard is demonstrating that the message > that the list relayed is the same in a semantic sense as the message that Phill > sent, even though it has the kind of changes that lists make, a tag in the > subject line, a footer at the bottom, and attachments stripped. That's hard indeed. We're probably better off just trusting the verified sender identity (second bullet). The author could have vouched the sender with a conditional signature... Ale