Re: [mailop] Null MX & Preference
> On Jul 14, 2016, at 7:00 PM, Suresh Ramasubramanian > wrote: > > On 15/07/16, 6:33 AM, "mailop on behalf of Mark Foster" > wrote: > >> Why would any other preference MX exist for a domain not intended to >> be used for email? > > They shouldn’t. Normally. But what if they do? Then delivery to the other MXes will likely be tried according to the normal rules (and be outside the scope of 7505). Null MX is only useful if it's the only MX for a domain. The weight of the null MX record doesn't really matter. "MX 0 ." is more an idiom than a strict template that must be followed. RFC 7505 extends that slightly by saying that your 7505-aware smarthost or MX might want to use a specific 5xx errors and enhanced status codes to flag a null MX, but that's icing on top of the existing 5321-implied gross behaviour. Cheers, Steve ___ mailop mailing list mailop@mailop.org https://chilli.nosignal.org/cgi-bin/mailman/listinfo/mailop
Re: [mailop] Null MX & Preference
On 15/07/16, 6:33 AM, "mailop on behalf of Mark Foster" wrote: > Why would any other preference MX exist for a domain not intended to > be used for email? They shouldn’t. Normally. But what if they do? ___ mailop mailing list mailop@mailop.org https://chilli.nosignal.org/cgi-bin/mailman/listinfo/mailop
Re: [mailop] Null MX & Preference
On 15/07/2016 12:55 p.m., Suresh Ramasubramanian wrote: On 15/07/16, 4:19 AM, "mailop on behalf of Brian Godiksen" wrote: That is what I was thinking. I wasn’t sure if there is a specific reason the preference is called out in the RFC. 0 is the lowest preference MX and will therefore be tried first, hopefully overriding any other higher preference MXs that may exist. Why would any other preference MX exist for a domain not intended to be used for email? ___ mailop mailing list mailop@mailop.org https://chilli.nosignal.org/cgi-bin/mailman/listinfo/mailop
Re: [mailop] Null MX & Preference
On 15/07/16, 4:19 AM, "mailop on behalf of Brian Godiksen" wrote: > That is what I was thinking. I wasn’t sure if there is a specific > reason the preference is called out in the RFC. 0 is the lowest preference MX and will therefore be tried first, hopefully overriding any other higher preference MXs that may exist. --srs ___ mailop mailing list mailop@mailop.org https://chilli.nosignal.org/cgi-bin/mailman/listinfo/mailop
Re: [mailop] Null MX & Preference
That is what I was thinking. I wasn’t sure if there is a specific reason the preference is called out in the RFC. Thanks, Brian > On Jul 14, 2016, at 6:34 PM, Mark Foster wrote: > > Surely if the MX record is declared as a . then the preference is irrelevant? > > > On 15/07/2016 8:38 a.m., Brian Godiksen 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. 2530IN MX 10 . >> >> Is anyone ignoring the preference number in their implementation? >> >> Thanks, >> Brian >> ___ >> 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
Re: [mailop] Null MX & Preference
Surely if the MX record is declared as a . then the preference is irrelevant? On 15/07/2016 8:38 a.m., Brian Godiksen 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. 2530IN MX 10 . Is anyone ignoring the preference number in their implementation? Thanks, Brian ___ 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
Re: [mailop] Null MX & Preference
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 wrote: > indeed... > > I think the null MX makes sense when there is an A or 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 wrote: >> >> >> > On Jul 14, 2016, at 2:39 PM, Franck Martin 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 wrote: >> > >> > > On Jul 14, 2016, at 1:38 PM, Brian Godiksen >> > > 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. 2530IN 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
Re: [mailop] Null MX & Preference
indeed... I think the null MX makes sense when there is an A or 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 wrote: > > > On Jul 14, 2016, at 2:39 PM, Franck Martin 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 wrote: > > > > > On Jul 14, 2016, at 1:38 PM, Brian Godiksen > 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. 2530IN 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
Re: [mailop] Null MX & Preference
> On Jul 14, 2016, at 2:39 PM, Franck Martin 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 wrote: > > > On Jul 14, 2016, at 1:38 PM, Brian Godiksen 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. 2530IN 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
Re: [mailop] Null MX & Preference
I kind of see the null MX as a way to say that this domain does not send emails. 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 wrote: > > > On Jul 14, 2016, at 1:38 PM, Brian Godiksen > 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. 2530IN 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
Re: [mailop] Null MX & Preference
> On Jul 14, 2016, at 1:38 PM, Brian Godiksen 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. 2530IN 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] Null MX & Preference
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. 2530IN MX 10 . Is anyone ignoring the preference number in their implementation? Thanks, Brian ___ mailop mailing list mailop@mailop.org https://chilli.nosignal.org/cgi-bin/mailman/listinfo/mailop
