:date: 2019-12-31

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Tuesday, December 31, 2019
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Some mailman list members don't receive any mail
================================================

Still working on :ticket:`3339`.

It seems that the easiest way to reproduce our problem it to have our own mail
server, i.e.postfix at LF does not use a relay. Because then we can at least see
what happens.  And this is what happens when I try to send something to any
recipient `@hot.ee`::

  Dec 30 04:39:52 myhostname-1 postfix/smtp[5611]: 1E78DAC52:
  to=<lucsaffre@hot.ee>, relay=mx1.hot.ee[194.126.101.119]:25, delay=6.2,
  delays=0.02/0.05/6.1/0.1, dsn=4.3.2, status=deferred (host
  mx1.hot.ee[194.126.101.119] said: 450 4.3.2 Service currently unavailable (in
  reply to RCPT TO command))

The system admin of hot.ee thinks that maybe I am greylisted and suggests that I
increase my timeout, iow to be more patient when waiting for their answer.

As explained `here
<https://serverfault.com/questions/24121/understanding-a-postfix-log-file-entry>`_::

  # Message delivery time stamps
  # delays=a/b/c/d, where
  #   a = time before queue manager, including message transmission
  #   b = time in queue manager
  #   c = connection setup including DNS, HELO and TLS;
  #   d = message transmission time.

So the "connection setup including DNS, HELO and TLS" took 6.1 seconds.  I
looked for configuration settings that might instruct postscript to stop
waiting::

  $ sudo postconf | grep timeout
  connection_cache_protocol_timeout = 5s
  lmtp_connect_timeout = 0s
  postscreen_upstream_proxy_timeout = 5s
  smtpd_upstream_proxy_timeout = 5s
  # (showing only entries with less than 10s)

I looked up the meaning of those settings in the `docs
<http://www.postfix.org/postconf.5.html>`__ but could not find anything that
looks worth a test.


I verified that our server is not listed at spamhaus::

  https://www.spamhaus.org/query/ip/167.114.229.225