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295427Re: Connection Speed

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  • Viktor Dukhovni
    Sep 12, 2013
      On Thu, Sep 12, 2013 at 09:12:59AM -0400, Roman Gelfand wrote:

      > We have a program which every so often sends a request, using chilkat,
      > to postfix to send out email with attachment. With every send it has
      > to connect to postfix using sasl authentication. Each send appears to
      > take a long time. In the absence of more detailed information, I am
      > guessing the connection is taking most of the time.

      Don't guess measure. The mail logs record four delay measurements for
      each message:

      postfix/smtp[<pid>]: <queue_id>: to=<rcpt>, ... delays=a/b/c/d, ...

      The components of the "delays" field are:

      a. Time elapsed between message creation and the message entering
      the active queue. With SMTP the clock starts at the first
      accepted "RCPT TO:" command. This does not include the time
      from the client's TCP SYN to initiate the connection until
      the server responds with "250" to "MAIL FROM:".

      The start time is that of the log entry of the form:

      postfix/smtpd[<pid>]: <queue-id>: client=...

      If your client's IP address triggers slow (failing) PTR
      lookups, or slow forward lookups of the resulting name
      that time is not seen in the Postfix logs as the
      first log message

      postfix/smtpd[<pid>]: connect from ...

      is logged after attempting to reverse resolve the client's
      IP address.

      b. Time spent in the active queue, large delays here show a congested
      destination or an overall congested queue.

      c. Time taken to connect to the remote destination, from the delivery
      agent receiving the request to deliver the message to the beginning
      of the mail transaction (with SMTP, sending MAIL FROM:)

      d. Time taken to complete the mail transaction.

      Report all logging for your "slow" deliveries, from the "connect from ..."
      message with the same process id as the "smtpd: <queue_id>: client=" message
      including all messages with that queue-id, until the "disconnect from".

      You may find the Perl script in:

      http://www.mail-archive.com/postfix-devel@.../msg00292.html

      useful.

      --
      Viktor.
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