[Mailman-Users] delayed distribution of messages

Mark Sapiro mark at msapiro.net
Sat Sep 17 17:42:59 CEST 2011

Lluis Montoliu wrote:
>I am responsible for a list of ~500 members and other much smaller  
>(<25 members). All these lists, specially the largest, are  
>experiencing unexpected delays in distributing messages of about 45-60  
>min from sending a message to the list and the message being  
>distributed. This is very problematic and makes the use of these lists  
>a pain, specially for maintain a dynamic discussion on any subject.
>The mail system itself seems to be OK. If I do send a message to the  
>same 500 members from a PHP script the message gets distributed  
>I don't have root privileges although we are on our own (administered)  
>server. All I can do is complain before my hosting services and they  
>say they can't do much and refer to internal mailman problems to  
>explain this poor performance (that I haven't seen before in other  

The first thing you need to do is examine the Received: headers in one
of these delayed messages to determine where the delay occurs. It may
or may not even involve Mailman. Note that Received: headers are added
at the top of the headers by each MTA as it receives the message,
thus, the chain reads chronologically from bottom to top.

Yo need two find the two headers which indicate delivery to Mailman and
delivery from Mailman. For example, in the message to which I'm
replying as received by me from the list, the two relevant headers are:

Received: from albatross.python.org (localhost [])
	by mail.python.org (Postfix) with ESMTP id 3S1Gcn4GdGzP1M
	for <mark at msapiro.net>; Sat, 17 Sep 2011 16:50:49 +0200 (CEST)


Received: from albatross.python.org (localhost [])
	by mail.python.org (Postfix) with ESMTP id 3S15yp2hlbzNvQ
	for <mailman-users at python.org>; Sat, 17 Sep 2011 10:20:50 +0200 (CEST)

The bottom header indicates the post was delivered to mail.python.org
atSat, 17 Sep 2011 10:20:50 +0200, and the top header indicates the
message to me was received from Mailman at Sat, 17 Sep 2011 16:50:49
+0200. Thus, there was a delay of about 6 hours and 30 minutes between
delivery to Mailman and delivery from Mailman. In this case, this
delay is explained by the fact the you are a new list member and your
post was moderated as noted by the header

X-Mailman-Approved-At: Sat, 17 Sep 2011 16:50:04 +0200

Thus, there was actually only a 45 second delay between moderator
approval and delivery from Mailman.

Anyway, if the above indicates the delay is between delivery to Mailman
and delivery from Mailman, you need to examine Mailman's 'smtp' and
'smtp-failure' logs for 'long' processing times and or temporary
failures to get additional clues.

>However, I wanted to ask this community whether there are any other  
>known bugs or issues to take into account that might impair list  
>performance and delay the distribution of messages,

There are no known bugs but there are several potential issues that
could affect this, but we need more information to say more.

Mark Sapiro <mark at msapiro.net>        The highway is for gamblers,
San Francisco Bay Area, California    better use your sense - B. Dylan

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