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Re: Our postfix works fine, but it is very slow when we send newsletter

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  • Jeroen Geilman
    ... How is DNS set up in comparison with the previous server ? Badly configured DNS can certainly slow things down, especially on outgoing mail. Any even
    Message 1 of 6 , Feb 21, 2013
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      On 02/20/2013 07:16 PM, Vince Wang wrote:

      Hello,

       

      We have a configured postfix email server worked well when we had it on the public IP.
      After we moved  it behind our firewall on a intranet with ip 192.168.xxx.xxx, we found it is very slow when we send newsletter.


      How is DNS set up in comparison with the previous server ?
      Badly configured DNS can certainly slow things down, especially on outgoing mail.
      Any even moderately busy mailserver should have a local DNS cache.

        Server info:     Ubuntu 10.4 32 bit running on 4cpus + 8GB memory VM ( VMware host )


      A 32-bit OS with 8GB of memory ? only 3.5GB of that will be used, ever.
      Regardless, postfix hardly uses any memory, unless you are receiving hundreds of 10MB messages concurrently.
      That is much more relevant for mail performance is storage I/O - and you don't mention anything related to storage.

      As I just start learning about  postfix so  I tried to figure how it works.  I sent a newsletter to 1100 members last week

      How many *messages* did you send ?

      and monitored  the queue in the webmin and mailq, and the postfix log.  After I clicked the "send" button on our web page, I  found that the messages are added into the queue for 15 minutes and then I saw messages are sent out  from the log file for around 15 minutes.   


      So you are seeing an average processing speed of 1.2 messages per second before queue, and another average 1.2 messages per second during delivery ?
      Show logs that exhibit these delays; postfix logs detailed delay statistics for each message delivered.

        content_filter = smtp-amavis:[127.0.0.1]:10024


      If you're submitting via smtpd(8) then all locally submitted mail will be scanned, which is patently useless in this case.

      smtpd_recipient_limit = 100000

      That is insane.

      qmgr_message_active_limit = 50000

      line_length_limit = 204800

      maximal_queue_lifetime = 2d

      queue_run_delay = 4000s

      minimal_backoff_time = 4000s


      Do not mess with these values unless you know exactly what they do.

      No logs, so how do you expect us to deduce what is happening here ?


      -- 
      J.
      
    • Jeroen Geilman
      ... ... how ? Either pickup(8) or smtpd(8) do the queueing; the qmgr only SENDS mail. There could be disk I/O contention, sure, but that would never translate
      Message 2 of 6 , Feb 21, 2013
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        On 02/21/2013 03:34 PM, Ralf Hildebrandt wrote:
        > It could be that the process injecting the mails into the queue is
        > stalling the queuemanager, thus sending out can only begin AFTER the
        > injection period.

        ... how ?

        Either pickup(8) or smtpd(8) do the queueing; the qmgr only SENDS mail.
        There could be disk I/O contention, sure, but that would never translate
        into a scenario where no mail could be de-queued before all mail was
        finished queueing.
        These are wholly separate processes after all, and the only point of
        contact is the mail queue, which is concurrent read-write by design.
        By default, there may be many simultaneous processes accessing the queue
        (100 each of smtpd and smtp, for starters.)

        Of course, it could be that he really is sending every single submitted
        message through amavisd and then re-injecting into postfix, thus
        effectively forcing every single message through the pipeline twice.

        This would be inane no matter what kind of IP address it has, but the
        cause of the delays would be the content_filter, nothing else.

        There are settings in amavisd-new that govern what to do when a message
        originates from a trusted or untrusted IP range, offering the option to
        pass it through without scanning.
        If this was impacted by the IP change, that could easily explain the
        delays - but they would still never be sequential.

        Of course, you did ask for logs as well :)

        --
        J.
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