Doesn't receive emails, sure. Doesn't send emails, I look for the "SPF lockdown." Lots of places publish this as an SPF record: "v=spf1 -all"
And I've been recommending people publish that if they have no plan to send email using that domain. It's an easy DNS test to confirm that a given domain doesn't send mail. (And then probably doesn't receive email, either. Seems to be a better guess in this direction than in the other direction.) -- Al Iverson www.aliverson.com (312)725-0130 On Thu, Jul 14, 2016 at 5:16 PM, Franck Martin via mailop <mailop@mailop.org> wrote: > indeed... > > I think the null MX makes sense when there is an A or AAAA on the same > domain. It stops the mail server to try to deliver and wait 4+ days to > bounce the message. > > Other MX that are always fun to use: > > MX 10 localhost > > ;) > > On Thu, Jul 14, 2016 at 2:46 PM, Steve Atkins <st...@blighty.com> wrote: >> >> >> > On Jul 14, 2016, at 2:39 PM, Franck Martin <fmar...@linkedin.com> wrote: >> > >> > I kind of see the null MX as a way to say that this domain does not send >> > emails. >> >> Eh... only indirectly, implicitly and only kinda. >> >> 0-mx-dot states that the domain does not receive email for any address. It >> doesn't say anything directly about whether mail is sent using email >> addresses in that domain. >> >> If you believe that you must be able to deliver an asynchronous bounce for >> any message you receive, and you receive mail with an 821.From that you know >> is undeliverable then it's reasonable to treat that mail with a lot of >> suspicion. >> >> But 0-mx-dot is not an explicit statement by the domain owner of "mail is >> not sent using this domain". That'd be an SPF -all, or something DMARCy. >> >> Cheers, >> Steve >> >> > So it is more a test on the receiving side than on the sending side. >> > >> > On Thu, Jul 14, 2016 at 2:04 PM, Steve Atkins <st...@blighty.com> wrote: >> > >> > > On Jul 14, 2016, at 1:38 PM, Brian Godiksen <br...@socketlabs.com> >> > > wrote: >> > > >> > > I noticed inconsistencies in how domains are publishing null MX >> > > records. In RFC7505 it states these records should be published with a >> > > preference number 0. I am seeing a variety of preferences specified >> > > though. >> > > >> > > Example: >> > > >> > > ;; QUESTION SECTION: >> > > ;hotmai.com. IN MX >> > > >> > > ;; ANSWER SECTION: >> > > hotmai.com. 2530 IN MX 10 . >> > > >> > > Is anyone ignoring the preference number in their implementation? >> > >> > More generally, is anyone special-casing this rather than just treating >> > it as an idiomatic way of creating an email address that immediately fails >> > to deliver? >> > >> > Cheers, >> > Steve >> > _______________________________________________ >> > mailop mailing list >> > mailop@mailop.org >> > https://chilli.nosignal.org/cgi-bin/mailman/listinfo/mailop >> > >> >> >> _______________________________________________ >> mailop mailing list >> mailop@mailop.org >> https://chilli.nosignal.org/cgi-bin/mailman/listinfo/mailop > > > > _______________________________________________ > mailop mailing list > mailop@mailop.org > https://chilli.nosignal.org/cgi-bin/mailman/listinfo/mailop > _______________________________________________ mailop mailing list mailop@mailop.org https://chilli.nosignal.org/cgi-bin/mailman/listinfo/mailop
