Duped Messages (was Re: Please split this list!)

[Jelle De Loecker]

Can something be done about it? I'm getting every message at least 2 
times, mostly 3 times.

/Met vriendelijke groeten,/

*Jelle De Loecker*
Kipdola Studios - Tomberg


Joel Newkirk schreef:
> Rui Miguel Silva Seabra wrote:
>   
>> Since we're talking about the mailing lists, I still receive (randomly),
>> three repeated mails, two repeated mails, etc...
>>
>> This mail from Vasco... I received it three times already! :)
>>
>> Rui
>>
>> On Mon, Sep 01, 2008 at 12:24:03PM +0100, vasco.nevoa at sapo.pt wrote:
>>   
>>     
>
> If you examine the email headers you can see that the 'received' header 
> documenting where the mail server handling the list (sita.openmoko.org 
> running exim 4.63) received the message from the sender's mailserver 
> (IE, their ISP's mailserver) differs from one copy to the next - this 
> means that either the sending server is failing to recognize that the 
> message has been delivered and resends, possibly the receiving server is 
> failing to send the acknowledgement of receipt at the end of the SMTP 
> transaction (at least in a timely fashion), so the sending server 
> automatically retries.
>
> Received: from relay1.ptmail.sapo.pt ([212.55.154.21] helo=sapo.pt)
> 	by sita.openmoko.org with smtp (Exim 4.63)
> 	(envelope-from <vasco.nevoa at sapo.pt>) id 1Ka7yh-0002Ow-Ha
> 	for community at lists.openmoko.org; Mon, 01 Sep 2008 13:55:37 +0200
>
> Received: from relay1.ptmail.sapo.pt ([212.55.154.21] helo=sapo.pt)
> 	by sita.openmoko.org with smtp (Exim 4.63)
> 	(envelope-from <vasco.nevoa at sapo.pt>) id 1Ka7fK-0005dL-Pf
> 	for community at lists.openmoko.org; Mon, 01 Sep 2008 13:55:37 +0200
>
> Received: from relay1.ptmail.sapo.pt ([212.55.154.21] helo=sapo.pt)
> 	by sita.openmoko.org with smtp (Exim 4.63)
> 	(envelope-from <vasco.nevoa at sapo.pt>) id 1Ka7ZO-0003bU-8Q
> 	for community at lists.openmoko.org; Mon, 01 Sep 2008 13:55:21 +0200
>
>
> Notice that the message ID differs between the three copies.
> This tells us that this is the point (when sapo.pt mailserver delivers 
> to sita.openmoko.org mailserver) where the failure occurs.  If it were 
> the mailinglist server sending dupes, this header would be identical 
> among all copies.
>
> Also, it doesn't depend on sending mailserver software, I've noted it 
> happening with qmail as sender, exim, gmail.com, and others.  (even 
> mail.openmoko.org sometimes, such as Andy Green's reply to the '3G 
> modem' thread)  Based on past experience as admin of a cluster of 
> mailservers that sometimes exceeded 1 million incoming SMTP connections 
> per day, I suspect that either spam filtering or some testing for ML 
> (IE, 'is this sender permitted to post?') takes place AFTER receiving 
> the message but BEFORE telling the sending server that message was 
> received, and is periodically taking longer than the sending server's 
> SMTP timeout, so the sender gives up on the connection and tries again - 
> meanwhile the exim server handling the ML eventually accepts the 
> message.  My suspicion is that the load on the (virtual?) server hosting 
> the ML is getting to a level where processing messages sometimes takes 
> longer than some sending servers are willing to wait.  Properly, in such 
> a situation, the sending server is supposed to resend, and the receiving 
> server is supposed to discard the message it failed to fully receive 
> before the connection was broken.
>
> Unfortunately my mailserver experience is with surgemail, qmail, 
> sendmail, and some exchange (ick), but I've never worked with Exim, so I 
> can't suggest anything specific to check in the server config.  (When 
> I've seen this caused by receiving mailserver it was most often qmail, 
> and was caused by improperly configured/limited spawning that exceeded 
> available RAM instead of deferring excess inbound connections - once 
> dipping into swap, all bets are off regarding timely responses)
>
> j
>
>
>
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>   
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