[Mailman-Users] odd empty bounce message generated upon posting toa mailing list

Mark Sapiro msapiro at value.net
Fri Jun 1 03:38:42 CEST 2007

Jon Pauli wrote:
>I have a couple of mailing lists and every time anyone- member or
>non-member posts, everything works fine but the list owner gets
>1)An uncaught bounce notification containing an empty attachment
>called ForwardedMessage.eml. Thunderbird is the MUA so I'm guessing it
>is responsible for determining how to interpret the attachment, but
>even if I save it as a text file it is a 2 byte long file with no
>visible characters in it...I didn't take a hex editor to it. I
>understand why listowner gets these, I'm just not sure how it can work
>with a 2 byte file and no headers ;)

This is the message/rfc822 part attached to the bounce notification.
T'bird will call it ForwardedMessage.eml if it can't find a Subject:
in it which in this case, it can't because the message has no headers
and no body.

I think this represents a null message sent to the listnam-bounces
address, being detected as 'unrecognized' (not surprising) and
forwarded to the owner.

>2. An email where no subject and no sender appear in the MUA. The
>headers are as follows:
>Delivered-To: me at mydomain.com
>Return-Path: <
>mailman-bounces at mail.mydomain.com>
>Received: from [] (softdnserr [])
>by mail.mydomain.com with esmtp; Thu, 31 May 2007 09:57:36 -0500id
>Sender: mailman-bounces at mail.mydomain.com
>Errors-To: mailman-bounces at mail.mydomain.com
>Message-ID: <courier.465EE260.00010B2E at mydomain>
>Date: Thu, 31 May 2007 09:57:36 -0500
>To: undisclosed-recipients: ;

This appears to be the result of a null message delivered to the
listname-owner address with a few headers added by Mailman and the
outgoing MTA.

>The interesting things I noticed are:
>1. The Received: header line is wrong. The mail server has a DNS
>server running on it as well as the MTA.  its IP is NOT
>10.22 There is no on my network. This happens only for
>mailman emails. I don't recall having to set any IPs when I set up
>mailman. What is wrong here?

Your outgoing MTA thinks its 'localhost' is Check the
MTA configuration for any occurrence of

>2. The end of the Message-ID: line contains only mydomain, not say,
>mydomain.com like non-mailman emails.

I think your MTA made up this message-id, so again, look to your MTA.

>3. There is no Sender showing up in the MUA but the Sender: header is
>present. It looks like Thunderbird maybe uses the From: header instead
>of the Sender header despite naming the column where this would appear

This is really a T'bird question, but yes, what T'bird labels as
'sender' in the folder contents pane comes from the From: header.

It seems what is happening is for every incoming message to
listname at example.com, a null (empty) message is also delivered to
listname-bounces at example.com and listname-owner at example.com.

When you say "every time anyone- member or non-member posts", do
non-member posts get held, rejected or discarded? If so, I think that
says these extra null messages are created at incoming message time,
probably from some mis-configuration of aliases or routers/transports
in the incoming MTA.

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

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