Thank you, John. I agree that it's an edge case and not worth addressing separately.
Eric Chudow DoD Cybersecurity Mitigations -----Original Message----- From: John Levine <jo...@taugh.com> Sent: Thursday, November 19, 2020 11:04 PM To: dmarc@ietf.org Cc: Chudow, Eric B CIV NSA DSAW (USA) <eric.b.chudow....@mail.mil> Subject: Re: [dmarc-ietf] Second WGLC for draft-ietf-dmarc-psd: Definition of NP In article <553d43c8d961c14bb27c614ac48fc03128116...@umechpa7d.easf.csd.disa.mil> you write: >Section 2.7. defines a non-existent domain as "a domain for which there >is an NXDOMAIN or NODATA response for A, AAAA, and MX records. This is >a broader definition than that in NXDOMAIN [RFC8020]." This should be >sufficient for determining that the domain is not intended to be used and >therefore could have a more stringent policy applied. > >The idea of looking for a "mail-enabled domain" based on if an "MX record >exists or SPF policy exists" is interesting. >Although there may be domains that send email but not receive email and so may >not have an MX record. These days I think you will find that if the domains in your bounce address and your From: headers don't have an MX or A record, very few recipients will accept your mail. This seems like an edge case. In practice I find that the domains caught by the Org domain or I suppose PSD have A records but no mail server because they're actually web hosts rather than mail hosts. We have the Null MX to indicate that a domain receives no mail and SPF plain -all to indicate that it sends no mail so I hope we don't try to reinvent these particular wheels. R's, John _______________________________________________ dmarc mailing list dmarc@ietf.org https://www.ietf.org/mailman/listinfo/dmarc
