>Today, messages can just disappear on the way to the user's mailbox >(often at or after that last-hop MTA). They do so without NDNs out >of fear of blowback, and they do so for two main reasons. ... You know, DNSBLs make mystery disappearances less likely, not more. The DNSBLs that most people use are typically checked at SMTP time, sp MTAs can give a 5xx rejection using the TXT record from the DNSBL that identifies why the mail was rejected. Even if the DNSBL isn't in the rejection message, there aren't that many lists that are widely enough used to matter, and since DNSBL listings (unlike the private per-system blacklists that are the most likely alternative) are by their nature public, it is easy enough to check a bunch of them and see if you're on one of them, thereby identifying the problem. The other approach is to use them in a scoring filter, but they'll do what they do whether or not they mix DNSBLs into the score. >Unlike you, I don't see "overwhelming community consensus for >this mechanism". Aw, come on. There's a billion and a half mailboxes using the Spamhaus DNSBLs, on systems ranging from giant ISPs down to hobbyist Linux boxes. R's, John _______________________________________________ Ietf@xxxxxxxx https://www.ietf.org/mailman/listinfo/ietf