RE: [exim] Help Required - Exim 3.36 outgoing email with lar…

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Author: Ebiz Analysis
Date:  
To: exim-users
Subject: RE: [exim] Help Required - Exim 3.36 outgoing email with large# NDR's looping
Hi Adrian,

My initial suspicions were leaning towards Outlook alone but...

When the emails were reported arriving every ~10 mins we switched off the
clients PC and unplugged it from the network. Thus the machine was incapable
of sending multiple messages. As far as we are able to be certain the
machine only ever sent one copy of the email to the server (checked on
client and server). Even after allowing for any mail queues to flush the
emails just kept on arriving.

I agree that it is entirely probable that a bug in Outlook caused the
problem but I am keen to identify and understand the failure mechanism.

For example, is it possible that if Outlook had created a message with a
mal-formed addressee list that the MTA would interpret the addresses in such
a way that when it got an NDR or multiple NDRs it would try to re-send to
the entire list?

The admin for the mail server running Exim was able to delete the message
from the queue which gave temporary respite to the problem. But in due
course (~1 day) the problem started again. This whilst the client PC still
offline.

I think that either the size of the addressee list (~350) or the number of
NDR's might be relevant but I don't know enough about Exim in depth to
hypothesise any further.

Rgds

Julian



-----Original Message-----
From: Adrian Phillips,,, [mailto:a.phillips@met.no]
Sent: 02 December 2004 10:13
To: info@???
Cc: exim-users@???
Subject: Re: [exim] Help Required - Exim 3.36 outgoing email with large#
NDR's looping

>>>>> "Julian" == Ebiz Analysis <info@???> writes:


    Julian> One of my customers has accidentally sent an email cc'd to
    Julian> every entry in their Outlook Address Book.


    Julian> The list of addresses contained a high proportion of
    Julian> invalid email addresses.


    Julian> The MTA now appears to be retrying to send this email to
    Julian> the entire address list once every ~10 mins.


Why the MTA - exim will only retry those addresses it failed to send to, not
all the addresses it succeeded in sending.

    Julian> It has been doing this incessantly for the past 10 days.


    Julian> This has resulted in the recipients with valid email
    Julian> addresses receiving the mail hundreds of times.  The
    Julian> originating mailbox has been flooded with thousands of
    Julian> NDR's.


This sounds more like an Outlook problem than an exim problem. If it was
just exim the message could easily be deleted from the queue.

Sincerely,

Adrian

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