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Re: Better to do 550 instead of 450 for these?

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  • Roger B.A. Klorese
    ... How is NXDOMAIN any more a hard failure? An authoritative server could be temporarily misconfigured...
    Message 1 of 13 , Jan 1, 2006
      Victor Duchovni wrote:
      > Postfix never returns 5XX for temporary lookup problems, even when it
      > returns 5XX for NXDOMAIN and other hard failures.


      How is NXDOMAIN any more a "hard" failure? An authoritative server
      could be temporarily misconfigured...
    • Roger B.A. Klorese
      ... Fair enough. But I m inclined to have an SMTP client believe an SMTP server but question everything else.
      Message 2 of 13 , Jan 1, 2006
        Bastian Blank wrote:
        > Why do you respect 5xx replies from a downstream server and bounce the
        > message? It may be temporarily misconfigured.
        >


        Fair enough. But I'm inclined to have an SMTP client believe an SMTP
        server but question everything else.
      • Len Conrad
        ... hard for me is negative protocol response (instead of no response). DNS NXDOMAIN or NODATA, or SMTP 5xx ain t my responsibility to mind-read, guess,
        Message 3 of 13 , Jan 1, 2006
          >>Postfix never returns 5XX for temporary lookup problems, even when it
          >>returns 5XX for NXDOMAIN and other hard failures.
          >
          >
          >How is NXDOMAIN any more a "hard" failure? An authoritative server
          >could be temporarily misconfigured...

          "hard" for me is negative protocol response (instead of no
          response). DNS NXDOMAIN or NODATA, or SMTP "5xx"

          ain't my responsibility to mind-read, guess, and hedge that their
          server is misconfigged. The sooner THEY pay for THEIR problems, the
          better off we all are.

          Len


          _____________________________________________________________________
          http://IMGate.MEIway.com : free anti-spam gateway, runs on 1000's of sites
        • Roger B.A. Klorese
          ... To me, the world is not me vs. them -- the goal is getting mail through, not scolding about other people s configurations.
          Message 4 of 13 , Jan 1, 2006
            Len Conrad wrote:
            > ain't my responsibility to mind-read, guess, and hedge that their
            > server is misconfigged. The sooner THEY pay for THEIR problems, the
            > better off we all are.


            To me, the world is not "me vs. them" -- the goal is getting mail
            through, not scolding about other people's configurations.
          • Arnt Gulbrandsen
            ... In that case, the name server tells you I am authoritative and I know there is no such domain . It s not telling you there never was , it s not telling
            Message 5 of 13 , Jan 1, 2006
              Roger B.A. Klorese writes:
              > Victor Duchovni wrote:
              >> Postfix never returns 5XX for temporary lookup problems, even when it
              >> returns 5XX for NXDOMAIN and other hard failures.
              >
              > How is NXDOMAIN any more a "hard" failure? An authoritative server
              > could be temporarily misconfigured...

              In that case, the name server tells you "I am authoritative and I know
              there is no such domain". It's not telling you "there never was", it's
              not telling you "there never will be", but what it is saying is
              qualitatively different from "I can't resolve that domain right now",
              and so deserves different treatment.

              Arnt
            • mouss
              ... so what? when they fix their system, then they ll post their mail! Systems should be optimized for the common case, not for rare cases. I prefer to get a
              Message 6 of 13 , Jan 1, 2006
                Roger B.A. Klorese a écrit :
                > Victor Duchovni wrote:
                >
                >> Postfix never returns 5XX for temporary lookup problems, even when it
                >> returns 5XX for NXDOMAIN and other hard failures.
                >
                >
                >
                > How is NXDOMAIN any more a "hard" failure? An authoritative server
                > could be temporarily misconfigured...
                >
                >

                so what? when they fix their system, then they'll post their mail!
                Systems should be optimized for the common case, not for rare cases.

                I prefer to get a bounce telling me that my DNS server is misconfigured
                than wait 4 days and get bounces for all the messages that my system
                sent during that period of time.

                If you don't like DNS failures, then don't base your mail decisions on
                that. DNS isn't safe. If you base your smtp setup on it, then you have
                the common denominator.
              • Len Conrad
                ... It s not 1995, or 2000. If mail admins won t/can t setup to look like part of the solution by now, then they pay whatever it costs to be part of the
                Message 7 of 13 , Jan 1, 2006
                  >To me, the world is not "me vs. them" -- the goal is getting mail
                  >through, not scolding about other people's configurations.

                  It's not 1995, or 2000.
                  If mail admins won't/can't setup to look like part of the solution by
                  now, then they pay whatever it costs to be part of the problem.

                  Len



                  _____________________________________________________________________
                  http://IMGate.MEIway.com : free anti-spam gateway, runs on 1000's of sites
                • Roger B.A. Klorese
                  ... It doesn t matter if it s 1995, 2000, 2005, or 2037 -- when stopping mail becomes more important than delivering mail, there s no point in there being
                  Message 8 of 13 , Jan 1, 2006
                    Len Conrad wrote:
                    > It's not 1995, or 2000.

                    It doesn't matter if it's 1995, 2000, 2005, or 2037 -- when stopping
                    mail becomes more important than delivering mail, there's no point in
                    there being mail.
                  • Victor Duchovni
                    ... This is getting seriously off-topic. Setting the DNS-based reject codes to 5XX is recommended as soon as one is confortable that the settings are correct.
                    Message 9 of 13 , Jan 2, 2006
                      On Sun, Jan 01, 2006 at 11:03:39PM -0800, Roger B.A. Klorese wrote:

                      > Len Conrad wrote:
                      > >It's not 1995, or 2000.
                      >
                      > It doesn't matter if it's 1995, 2000, 2005, or 2037 -- when stopping
                      > mail becomes more important than delivering mail, there's no point in
                      > there being mail.
                      >

                      This is getting seriously off-topic. Setting the DNS-based reject codes
                      to 5XX is recommended as soon as one is confortable that the settings
                      are correct. Persistent 4XX rejects that *don't* represent temporary
                      conditions are worse for the sender.

                      So either use "reject_unknown_sender_domain", ... with 5XX codes after
                      brief testing with 4XX codes (or soft_bounce=yes), or don't use them
                      at all.

                      Let's not drift into rec.talk.* territory. No off-topic followups please.

                      --
                      Viktor.

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