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281782Re: Dead Destination configuration

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  • Robert Schetterer
    Nov 30, 2011
    • 0 Attachment
      Am 01.12.2011 08:35, schrieb DN Singh:
      > 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.
      >
      > I tried configuring backoff-time, but it only comes into picture after
      > first attempt, which will get deferred, during time the destination is
      > differing. Next, I found
      > "default_destination_concurrency_failed_cohort_limit", but I was unable
      > to find to time for which it will remain dead. I know this is transport
      > configurable, so I can configure different time limits for different
      > destinations. This is because, I do not want any delivery attempts
      > during the time when a destination is marked dead.
      >
      > Is this possible? If yes, then how?
      >
      > Thanks.
      > DN Singh

      perhaps put some kind of scripted hold on them
      if they are always the same

      or use ideas from

      http://www.postfix.org/QSHAPE_README.html#backlog

      Postfix version 2.5 and later:

      In master.cf set up a dedicated clone of the "smtp" transport for
      the problem destination. In the example below we call it "slow".

      In main.cf configure a short delay between deliveries to the same
      destination.

      /etc/postfix/main.cf:
      transport_maps = hash:/etc/postfix/transport
      slow_destination_rate_delay = 1
      slow_destination_concurrency_failed_cohort_limit = 100

      /etc/postfix/transport:
      example.com slow:

      /etc/postfix/master.cf:
      # service type private unpriv chroot wakeup maxproc command
      slow unix - - n - - smtp

      See also the documentation for default_destination_rate_delay.

      This solution forces the Postfix smtp(8) client to wait for
      $slow_destination_rate_delay seconds between deliveries to the same
      destination.

      IMPORTANT!! The large slow_destination_concurrency_failed_cohort_limit
      value is needed. This prevents Postfix from deferring all mail for the
      same destination after only one connection or handshake error (the
      reason for this is that non-zero slow_destination_rate_delay forces a
      per-destination concurrency of 1).


      --
      Best Regards

      MfG Robert Schetterer

      Germany/Munich/Bavaria
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