On Sun 21/Jul/2019 18:53:35 +0200 Scott Kitterman wrote: >> >>> Keep in mind that senders do send from what we call non-existent domains for >>> reasons that seem good and sufficient to them. Let's take that as a fact, >>> whether it makes sense to us or not. >> >> >> Fair enough. Let me quote the current spec: >> >> A.4. Domain Existence Test >> >> A common practice among MTA operators, and indeed one documented in >> [ADSP], is a test to determine domain existence prior to any more >> expensive processing. This is typically done by querying the DNS for >> MX, A, or AAAA resource records for the name being evaluated and >> assuming that the domain is nonexistent if it could be determined >> that no such records were published for that domain name. >> >> The original pre-standardization version of this protocol included a >> mandatory check of this nature. It was ultimately removed, as the >> method's error rate was too high without substantial manual tuning >> and heuristic work. There are indeed use cases this work needs to >> address where such a method would return a negative result about a >> domain for which reporting is desired, such as a registered domain >> name that never sends legitimate mail and thus has none of these >> records present in the DNS. > > Yes, but that was for a different use case. It was , AIUI, considered that > reporting could be skipped on such 'non-existant' domains, but that proved > problematic since such domains as these are used in mail.
Wasn't it for rejecting non-existent domains? That is, IIRC, <sciencefiction> as if there were a root DMARC record (_dmarc.) with np=reject.</sciencefiction> > 'np' doesn't have the same issue. It uses non-existence in a positive (do > some processing) not a negative sense (reporting can be skipped for these), > so the problems described in that paragraph are not only not relevant, the > paragraph supports the case for 'np'. Uh? (I don't understand your parenthesized phrase...) At any rate, the first paragraph gives a definition of non-existence equal to the one we've been discussing these days, doesn't it? Best Ale -- _______________________________________________ dmarc mailing list [email protected] https://www.ietf.org/mailman/listinfo/dmarc
