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Re: Dead Destination configuration

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  • Jeroen Geilman
    ... Why ? SMTP deferral and retry are built into the protocol; they work fine. The only reason I can think of that would make you want to handle this manually
    Message 1 of 41 , Dec 1, 2011
      On 2011-12-01 08:35, DN Singh wrote:
      > Hello Group,
      >
      > I am trying some extra configuration for postfix where it would mark
      > some destinations as undeliverable. I have found that there are some
      > destinations, start deferring the mails (may be greylisting) for a
      > particular period of time (times ranging from 1min to 4hrs), and after
      > the time window is over, they accept mails properly. So, I would like
      > to configure per-destination dead time limit, where Postfix would not
      > attempt any delivery at all to a destination for the mentioned time.

      Why ?

      SMTP deferral and retry are built into the protocol; they work fine.

      The only reason I can think of that would make you want to handle this
      manually is if you have such huge volumes that you see actual
      performance issues.

      Are you seeing performance issues ? Are there delays in delivery to
      other destinations ?



      --
      J.
    • Jeroen Geilman
      ... There are two solutions you can try: within one instance, or using a separate instance, which will have its own queue. Within one instance, you can use a
      Message 41 of 41 , Dec 7, 2011
        On 2011-12-06 10:02, DN Singh wrote: Can you please name the topic, so I can search about it? It would be of great help.

        On Mon, Dec 5, 2011 at 10:41 PM, Jeroen Geilman <jeroen@...> wrote:
        On 2011-12-05 15:36, DN Singh wrote:
        Yes, I tried to figure it out that way, but the numbers aren't constant.

        Have you considered that this is because your submission is not 100% flat ?
        If you submit or retry in bursts (and when they block you for a fixed period of time after denying access, you WILL see clumping) then why expect their rejections to follow a different pattern ?

        As the people with much experience and experimentation on this list suggest, run separate delivery routes - with separate queues - for these slow destinations.
        All this is very well documented in the list archives.

        --
        J.



        There are two solutions you can try: within one instance, or using a separate instance, which will have its own queue.

        Within one instance, you can use a so-called *slow transport* to deliver mail to problematic domains at greatly reduced speeds.

        The basic theory behind this is described in: http://www.postfix.org/TUNING_README.html#rope

        To push mail for example.com to such a slow transport, use a transport_maps entry:

            example.com    smtp:myslowtransport

        Where myslowtransport is a service defined in master.cf.

        The more flexible solution is to set up a second instance of postfix (on an arbitrary internal port, say 127.0.0.1:2525) and push all slow mail to that instance.

        You then have complete control over queue lifetimes, backoff schedules, retry mechanisms, custom errors or deferrals, etc etc etc.

        (Sorry, I couldn't find a mailing list example in the time it took me to write this :)


        -- 
        J.
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