>There would need to be more to it than just this. Can you develop the idea >more? What should be in the field if it's present? Should it be tied to >something else?
There's a general rule that you can't allow senders to make positive assertions about their mail without external validation of those assertions, for the obvious reason that spammers will lie. The last hundred times these sorts of list filtering questions came up, people proposed all sorts of techniques that basically boiled down to a whitelist of mailing lists. While I don't think that's a bad idea, it does seem to me that if such lists were useful, we would be using them by now. In practice, over the past two decades, whenever the mail system has changed in way that allows people to send mail that screws up mailing lists, the lists have adapted by making minor twiddles to keep out the mail that screws them up. The best known is in the mid 1990s when lists stopped forwarding mail from non-subscribers, to deter spammers like Krazy Kevin who used lists as mail amplifiers. It's the same reason lists strip attachments, or limit message sizes. If DMARC policies turn out to be a problem in practice for lists, the twiddles to keep out mail with policy assertions is not hard. As I noted a while back, it was a one-line config change in my mj2 setup to trap mail with an A-R header that shows p=none or p=quarantine. R's, John _______________________________________________ dmarc-discuss mailing list [email protected] http://www.dmarc.org/mailman/listinfo/dmarc-discuss NOTE: Participating in this list means you agree to the DMARC Note Well terms (http://www.dmarc.org/note_well.html)
