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 >
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