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Re: Enabling sender-dependent authentication only for fallback relay?

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  • Victor Duchovni
    ... You have to use a fallback relay setting that sends the mail to a second Postfix instance on your machine, and have that instance send all mail to the
    Message 1 of 10 , May 2, 2011
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      On Sun, May 01, 2011 at 09:46:51PM -0700, Rich Wales wrote:

      > [Short version of my question: Is there any way to enable sender-
      > dependent authentication *only* when mail is being sent out via my
      > smtp_fallback_relay host, and *not* when I am sending mail directly
      > to a destination MX? I do not have any "relayhost" defined because
      > I am trying to send mail directly to a destination.]

      You have to use a fallback relay setting that sends the mail to a second
      Postfix instance on your machine, and have that instance send all mail
      to the relay, with sender-dependent authentication.

      smtp_fallback_relay=[127.0.0.1]:10035

      This would be a full Postfix instance, not just another master.cf entry:

      http://www.postfix.org/MULTI_INSTANCE_README.html

      --
      Viktor.
    • Rich Wales
      ... Thanks, Victor. A followup question, if I may. Briefly, can you help me understand what is going on in a situation like mine that will require the use of
      Message 2 of 10 , May 2, 2011
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        > You have to use a fallback relay setting that sends the mail to a second
        > Postfix instance on your machine, and have that instance send all mail
        > to the relay, with sender-dependent authentication. This would be a full
        > Postfix instance, not just another master.cf entry:

        Thanks, Victor.

        A followup question, if I may. Briefly, can you help me understand what is
        going on in a situation like mine that will require the use of a second,
        completely separate Postfix instance (and precludes doing what I want to do
        in a separate master.cf entry)?

        Rich Wales
        richw@...
      • Victor Duchovni
        ... The mail must be handled by a second separately configured smtp(8) delivery agent, and therefore, must be placed in a separate queue, which requires a
        Message 3 of 10 , May 2, 2011
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          On Mon, May 02, 2011 at 02:00:52PM -0700, Rich Wales wrote:

          > > You have to use a fallback relay setting that sends the mail to a second
          > > Postfix instance on your machine, and have that instance send all mail
          > > to the relay, with sender-dependent authentication. This would be a full
          > > Postfix instance, not just another master.cf entry:
          >
          > Thanks, Victor.
          >
          > A followup question, if I may. Briefly, can you help me understand what is
          > going on in a situation like mine that will require the use of a second,
          > completely separate Postfix instance (and precludes doing what I want to do
          > in a separate master.cf entry)?

          The mail must be handled by a second separately configured smtp(8) delivery
          agent, and therefore, must be placed in a separate queue, which requires
          a separate instance.

          If the message were handed off to the same queue-manager it would loop.

          --
          Viktor.
        • Rich Wales
          ... Ah. And, not surprisingly, when I tried to solve my problem using an alternative smtp in my master.cf, it did precisely that -- the second smtp threw the
          Message 4 of 10 , May 2, 2011
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            > The mail must be handled by a second separately configured smtp(8)
            > delivery agent, and therefore, must be placed in a separate queue,
            > which requires a separate instance. If the message were handed off
            > to the same queue-manager it would loop.

            Ah. And, not surprisingly, when I tried to solve my problem using an
            alternative smtp in my master.cf, it did precisely that -- the second
            smtp threw the message back into the queue, and my one-and-only Postfix
            dutifully pulled it out of the queue and processed it all over again
            from scratch, leading to a loop.

            So I assume there's no way to tag messages in a single Postfix queue
            with some sort of "already processed once -- let the secondary smtp
            agent take care of this one" marker? Instead, doing this requires a
            separate Postfix instance (with its own separate queue)?

            Rich Wales
            richw@...
          • Victor Duchovni
            ... Yes, and this is no less efficient, and in fact the configuration is IMHO simpler, and mailq(1) output is more meaningful, ... -- Viktor.
            Message 5 of 10 , May 2, 2011
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              On Mon, May 02, 2011 at 02:33:31PM -0700, Rich Wales wrote:

              > > The mail must be handled by a second separately configured smtp(8)
              > > delivery agent, and therefore, must be placed in a separate queue,
              > > which requires a separate instance. If the message were handed off
              > > to the same queue-manager it would loop.
              >
              > Ah. And, not surprisingly, when I tried to solve my problem using an
              > alternative smtp in my master.cf, it did precisely that -- the second
              > smtp threw the message back into the queue, and my one-and-only Postfix
              > dutifully pulled it out of the queue and processed it all over again
              > from scratch, leading to a loop.
              >
              > So I assume there's no way to tag messages in a single Postfix queue
              > with some sort of "already processed once -- let the secondary smtp
              > agent take care of this one" marker? Instead, doing this requires a
              > separate Postfix instance (with its own separate queue)?

              Yes, and this is no less efficient, and in fact the configuration is
              IMHO simpler, and mailq(1) output is more meaningful, ...

              --
              Viktor.
            • Rich Wales
              ... Thanks again. As it turned out, I was able to find a way to authenticate to my web hosting service s outbound SMTP server using a single username/password
              Message 6 of 10 , May 2, 2011
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                > Yes, and this is no less efficient, and in fact the configuration
                > is IMHO simpler, and mailq(1) output is more meaningful, ...

                Thanks again.

                As it turned out, I was able to find a way to authenticate to my web
                hosting service's outbound SMTP server using a single username/password
                combo -- and thereby stop having to use sender-dependent authentication,
                and thus avoid the problems which accompanied the sending of my auth
                credentials to random servers, without needing to do anything complex.

                For the time being, I'm happy. :-) Thanks to everyone for their help.

                Rich Wales
                richw@...
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