>At least in the back-of-the-envelope scheme I suggested, the receiver >doesn't need to distinguish mailing lists: The originator's system finds >out where the mail is going, gets some information from the destination, >and signs that and sends it with the message. The mailing list sends >that along to the recipients. When my (one of the recipient's) server >looks at that info, it determines that the originator sent the message >directly to the mailing list, and I can tell that the mailing list sent >it to me. I still think it has security holes but it's worth arguing about, so I'll follow up on ietf-822, which seems relevant and hasn't been very busy. R's, John