[Mailman-Users] Duplicate posts to earthlink.com

Brad Knowles brad at shub-internet.org
Thu Nov 20 08:53:58 CET 2008

on 11/20/08 1:37 AM, Grant Taylor said:

> If my logic is correct, it should be the last server (Received: header 
> closest to the top of the message) that received the message that was 
> not duplicated.  If the two examples share one Received: header and then 
> subsequent (closer to the top) are different, it is the server that 
> generated last common Received header that is causing the duplication / 
> sending the message multiple times.

The problem is that you can't always be 100% certain which server is 
actually responsible.

I've seen cases where the receiving server generated a 4xx series error 
message after the end of the DATA section, or just plain timed out after 
the end of the DATA section, and the sending server thought it needed to 
retransmit the message.  But what really happened is that the receiving 
server actually accepted and delivered the message, and erroneously 
generated the error message, or didn't handle a timeout properly.

I've also seen cases where the sending server is at fault.

So, you at least know that there is a breakdown somewhere between the 
two machines in question, and you should be able to figure out who the 
respective administrators are, and work from there.  Once you actually 
confirm which machine is at fault, you know who you need to whack with 
the cluebat.

Brad Knowles <brad at shub-internet.org>
LinkedIn Profile: <http://tinyurl.com/y8kpxu>

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