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RE: Reject email

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  • Héctor Moreno Blanco
    Thanks for all the answers! They helped me quite a lot :) Regards. Héctor Moreno Blanco ... De: owner-postfix-users@postfix.org
    Message 1 of 12 , May 9, 2013
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      Thanks for all the answers!

      They helped me quite a lot :)

      Regards.

      Héctor Moreno Blanco



      -----Mensaje original-----
      De: owner-postfix-users@... [mailto:owner-postfix-users@...] En nombre de Reindl Harald
      Enviado el: jueves, 09 de mayo de 2013 14:27
      Para: postfix-users@...
      Asunto: Re: Reject email



      Am 09.05.2013 14:14, schrieb Stan Hoeppner:
      > On 5/9/2013 5:28 AM, Reindl Harald wrote:
      >>
      >> Am 09.05.2013 12:24, schrieb Héctor Moreno Blanco:
      >>> I would like to reject an email if the MX does not exist. We have
      >>> enable the setting /reject_unknown_sender_domain/ and
      >>> /reject_unknown_recipient_domain/. However, if the domain has DNS
      >>> and resolves it, the message is sent, and we don't want that
      >>
      >> this is a completly broken idea
      >
      > Not completely broken. It's not really "no MX" that Hector is after,
      > but undeliverable sender addresses in snowshoe spam. "No MX" would
      > fall under this umbrella

      if you have a A-record for "example.com" and you incoming mail-server is on this IP you do not need any MX record and postfix will happily use the A-record to deliver mail

      another story is if there is a MX-Record but the listed hostname does not resolve and at least for me the intention of "if the MX does not exist" is not clear enough if it means

      a) no MX record for the domain
      b) a MX record with a non-resloving hostname

      reject b) would be fine
      reject a) would be stupid



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    • Stan Hoeppner
      Normally I d avoid arguing with your Reindl as it simply clutters the list. However you made some invalid points that need to be corrected for those who may
      Message 2 of 12 , May 9, 2013
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        Normally I'd avoid arguing with your Reindl as it simply clutters the
        list. However you made some invalid points that need to be corrected
        for those who may browse the archives in the future.

        On 5/9/2013 7:26 AM, Reindl Harald wrote:

        > if you have a A-record for "example.com" and you incoming
        > mail-server is on this IP you do not need any MX record
        > and postfix will happily use the A-record to deliver mail

        When did you last come across a domain configured strictly for fallback
        to A? While RFC may require it, and some used it in the 70s and 80s, no
        receivers rely on fallback to A in 2013. Anyone versed sufficiently in
        SMTP to know of the existence of fallback to A isn't going to rely on
        it. They'll have proper MX records.

        > another story is if there is a MX-Record but the listed
        > hostname does not resolve and at least for me the intention
        > of "if the MX does not exist" is not clear enough if it means
        >
        > a) no MX record for the domain
        > b) a MX record with a non-resloving hostname
        >
        > reject b) would be fine

        Only if the response is 4xx. People fat finger records all the time.

        > reject a) would be stupid

        If generic and not selective then yes, but not because of fallback to A.
        The real problem here is legitimate send-only domains, such as some
        mailing lists, bulk mail campaigns, emergency alert and other
        notification systems, etc.

        --
        Stan
      • Reindl Harald
        ... keep this bullshit for you ... NOT SO LONG AGO a few years ago i was so naive and stupid to implement a DNS check in the verify-function of my
        Message 3 of 12 , May 9, 2013
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          Am 09.05.2013 16:44, schrieb Stan Hoeppner:
          > Normally I'd avoid arguing with your Reindl as it simply
          > clutters the list

          keep this bullshit for you

          > On 5/9/2013 7:26 AM, Reindl Harald wrote:
          >
          >> if you have a A-record for "example.com" and you incoming
          >> mail-server is on this IP you do not need any MX record
          >> and postfix will happily use the A-record to deliver mail
          >
          > When did you last come across a domain configured strictly for fallback
          > to A? While RFC may require it

          NOT SO LONG AGO

          a few years ago i was so naive and stupid to implement
          a DNS check in the verify-function of my php-framework
          to prevent import / subscribe to newsletter lists with
          undeliverable domains

          i had it to learn the hard way that RFC's are
          not only for fun

          >> another story is if there is a MX-Record but the listed
          >> hostname does not resolve and at least for me the intention
          >> of "if the MX does not exist" is not clear enough if it means
          >>
          >> a) no MX record for the domain
          >> b) a MX record with a non-resloving hostname
          >>
          >> reject b) would be fine
          >
          > Only if the response is 4xx. People fat finger records all the time

          that's their problem
          after fixing this the next mails would go through

          nobody expect that if he make mistakes in his DNS configs and is too
          lazy to verify what he configured that others configure their servers
          to help him

          with this attitude you would needto reject all with 4xx because
          someone could have make a mistake - this is a bad attitude in
          context of e-mail
        • Stan Hoeppner
          ... Nice etiquette... ... You missed the point entirely. I think this is because you are predisposed to argue with anyone who disagrees with you, even when
          Message 4 of 12 , May 9, 2013
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            On 5/9/2013 9:55 AM, Reindl Harald wrote:
            >
            > Am 09.05.2013 16:44, schrieb Stan Hoeppner:
            >> Normally I'd avoid arguing with your Reindl as it simply
            >> clutters the list
            >
            > keep this bullshit for you

            Nice etiquette...

            >> On 5/9/2013 7:26 AM, Reindl Harald wrote:
            >>
            >>> if you have a A-record for "example.com" and you incoming
            >>> mail-server is on this IP you do not need any MX record
            >>> and postfix will happily use the A-record to deliver mail
            >>
            >> When did you last come across a domain configured strictly for fallback
            >> to A? While RFC may require it
            >
            > NOT SO LONG AGO
            >
            > a few years ago i was so naive and stupid to implement
            > a DNS check in the verify-function of my php-framework
            > to prevent import / subscribe to newsletter lists with
            > undeliverable domains
            >
            > i had it to learn the hard way that RFC's are
            > not only for fun

            You missed the point entirely. I think this is because you are
            predisposed to argue with anyone who disagrees with you, even when they
            are correct and you are incorrect. Hence the preface in my previous reply.

            >>> another story is if there is a MX-Record but the listed
            >>> hostname does not resolve and at least for me the intention
            >>> of "if the MX does not exist" is not clear enough if it means
            >>>
            >>> a) no MX record for the domain
            >>> b) a MX record with a non-resloving hostname
            >>>
            >>> reject b) would be fine
            >>
            >> Only if the response is 4xx. People fat finger records all the time
            >
            > that's their problem
            > after fixing this the next mails would go through
            >
            > nobody expect that if he make mistakes in his DNS configs and is too
            > lazy to verify what he configured that others configure their servers
            > to help him

            Again you miss the point. The reason for a 4xx here is so the mail gets
            queued and can simply be flushed after the DNS or other error is
            corrected. Thus the message isn't needlessly returned to the sender.
            Most of such errors are found and corrected pretty quickly. Using a 4xx
            in this case keeps things more transparent to users, whether mine,
            yours, or the guy at the remote SMTP site.

            > with this attitude you would needto reject all with 4xx because
            > someone could have make a mistake - this is a bad attitude in
            > context of e-mail

            No, Reindl, this is called courtesy to fellow network operators. The
            only bad attitude here is yours. You display it both here and on the
            Dovecot list regularly. Being brash and arrogant is one thing. Most
            people dislike that but tolerate it. But the constant cursing and
            berating anyone who disagrees with you crosses the line.

            Frankly I'm surprised that Wietse and Victor have let you get away with
            this behavior for so long. I guess they're leaving it up to members to
            add you to local kill files...

            --
            Stan
          • Reindl Harald
            ... and what was your quoted line clown ? ... but your problem is that you are not correct
            Message 5 of 12 , May 10, 2013
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              Am 10.05.2013 08:26, schrieb Stan Hoeppner:
              > On 5/9/2013 9:55 AM, Reindl Harald wrote:
              >>
              >> Am 09.05.2013 16:44, schrieb Stan Hoeppner:
              >>> Normally I'd avoid arguing with your Reindl as it simply
              >>> clutters the list
              >>
              >> keep this bullshit for you
              >
              > Nice etiquette...

              and what was your quoted line clown ?

              >>> On 5/9/2013 7:26 AM, Reindl Harald wrote:
              >>>
              >>>> if you have a A-record for "example.com" and you incoming
              >>>> mail-server is on this IP you do not need any MX record
              >>>> and postfix will happily use the A-record to deliver mail
              >>>
              >>> When did you last come across a domain configured strictly for fallback
              >>> to A? While RFC may require it
              >>
              >> NOT SO LONG AGO
              >>
              >> a few years ago i was so naive and stupid to implement
              >> a DNS check in the verify-function of my php-framework
              >> to prevent import / subscribe to newsletter lists with
              >> undeliverable domains
              >>
              >> i had it to learn the hard way that RFC's are
              >> not only for fun
              >
              > You missed the point entirely. I think this is because you are
              > predisposed to argue with anyone who disagrees with you, even when they
              > are correct and you are incorrect. Hence the preface in my previous reply

              but your problem is that you are not correct
            • Reindl Harald
              ... most of these errors are corrected after someone complaints and with a 4xx it takes up to 5 days until this happens a wrong configuration is a wrong
              Message 6 of 12 , May 10, 2013
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                Am 10.05.2013 08:26, schrieb Stan Hoeppner:
                >> nobody expect that if he make mistakes in his DNS configs and is too
                >> lazy to verify what he configured that others configure their servers
                >> to help him
                >
                > Again you miss the point. The reason for a 4xx here is so the mail gets
                > queued and can simply be flushed after the DNS or other error is
                > corrected. Thus the message isn't needlessly returned to the sender.
                > Most of such errors are found and corrected pretty quickly. Using a 4xx
                > in this case keeps things more transparent to users, whether mine,
                > yours, or the guy at the remote SMTP site.

                most of these errors are corrected after someone complaints and with
                a 4xx it takes up to 5 days until this happens

                a wrong configuration is a wrong configuration
                period

                >> with this attitude you would needto reject all with 4xx because
                >> someone could have make a mistake - this is a bad attitude in
                >> context of e-mail
                >
                > No, Reindl, this is called courtesy to fellow network operators. The
                > only bad attitude here is yours. You display it both here and on the
                > Dovecot list regularly. Being brash and arrogant is one thing. Most
                > people dislike that but tolerate it. But the constant cursing and
                > berating anyone who disagrees with you crosses the line.

                diagree is one thing but disagree on clear technical facts is another

                > Frankly I'm surprised that Wietse and Victor have let you get away with
                > this behavior for so long. I guess they're leaving it up to members to
                > add you to local kill files...

                frankly i am surprised that you not attack Wietse sometimes after
                he rferes to some documentation flowed by "to unsubscribe....."
              • Wietse Venema
                ... OK. A large portion of list traffic is now from Reindl giving rude responses to new and old members of this list. Having an active list member is good, but
                Message 7 of 12 , May 10, 2013
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                  Reindl Harald:
                  > Am 10.05.2013 08:26, schrieb Stan Hoeppner:
                  > > On 5/9/2013 9:55 AM, Reindl Harald wrote:
                  > >>
                  > >> Am 09.05.2013 16:44, schrieb Stan Hoeppner:
                  > >>> Normally I'd avoid arguing with your Reindl as it simply
                  > >>> clutters the list
                  > >>
                  > >> keep this bullshit for you
                  > >
                  > > Nice etiquette...
                  >
                  > and what was your quoted line clown ?

                  OK. A large portion of list traffic is now from Reindl giving rude
                  responses to new and old members of this list.

                  Having an active list member is good, but his manners are not.

                  I unsubscribe Reindl Harald, and I encourage all Postfix list
                  moderators to do the same in the case that he returns.

                  Wietse
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