FAQ
We had an ugly situation occur yesterday.

Here's the summary:
1. 1+ Meg email sent to list with no size limit
2. An email user, who has a ccMail account that forwards his mail on to
another account outside the company, has his outside mailbox hit his quota
limit. (This user is also digested)
3. The MTA at the receiving end that detects the over quota and sends an
email back to the list itself (see below for mail headers as to why this
might happen).
4. Mailman sends this email back to everyone on the list including the
digested mail user, whose MTA then rejects the email for the same reason as
before.
5. Repeat steps 3 and 4 about every 8 minutes.

This loop continues until the system comes to a halt from a full /tmp
directory. On every iteration the mail message grew a little bigger
because the last email gets copied on to the reject message.

There are a few problems here, but I'm not sure which problem is the wrong
case and which solution I should pursue.


Problem #1. ccMail changes the headers when it processes the mail.

Here's the normal headers from a post to mailman (I've stripped the
Received lines):
From: Rich Ramos <rich at chi.mti.com>
To: test at chi.mti.com
Message-ID: <563517.996585740@[144.86.11.157]>
X-Mailer: Mulberry/2.1.0b3 (Mac OS X)
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii; format=flowed
Content-Transfer-Encoding: 7bit
Content-Disposition: inline
Subject: [Test] test to show headers
Sender: test-admin at chi.mti.com
Errors-To: test-admin at chi.mti.com
X-BeenThere: test at chi.mti.com
X-Mailman-Version: 2.0.3
Precedence: bulk
List-Help: <mailto:test-request at chi.mti.com?subject=help>
List-Post: <mailto:test at chi.mti.com>
List-Subscribe: <http://chi.mti.com/mailman/listinfo/test>,
<mailto:test-request at chi.mti.com?subject=subscribe>
List-Id: <test.chi.mti.com>
List-Unsubscribe: <http://chi.mti.com/mailman/listinfo/test>,
<mailto:test-request at chi.mti.com?subject=unsubscribe>
List-Archive: <http://chi.mti.com/mailman/private/test/>
Date: Tue, 31 Jul 2001 13:22:20 -0500

Here's the way the headers get changed by ccmail:
Message-Id: <0107319966.AA996603967 at ccmgate.mti.com>
X-Mailer: ccMail Link to SMTP R8.30.00.7
Date: Tue, 31 Jul 2001 13:22:20 -0700
From: Rich Ramos <rich at chi.mti.com>
To: <test at chi.mti.com>
Subject: [Test] test to show headers
MIME-Version: 1.0
Content-Type: multipart/mixed; boundary="simple boundary"

As you can tell it's quite a bit different. However I'm not totally clear
that even with the changed headers, that the destination MTA should have
sent the bounce message back to the list. With the From: and To: headers
the way they are why didn't the MTA send the bouce back to the From:
address?

Problem #2:
The message was being delivered to a digested user, however the bounces
happened every few minutes. Why didn't the digest get sent once and then
not again until the next interval for the digest?

Doesn't mailman have some mechanism to catch looping posts to a list?

-Rich

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  • Rich Ramos at Jul 31, 2001 at 6:47 pm
    We had an ugly situation occur yesterday.

    Here's the summary:
    1. 1+ Meg email sent to list with no size limit
    2. An email user, who has a ccMail account that forwards his mail on to
    another account outside the company, has his outside mailbox hit his quota
    limit. (This user is also digested)
    3. The MTA at the receiving end that detects the over quota and sends an
    email back to the list itself (see below for mail headers as to why this
    might happen).
    4. Mailman sends this email back to everyone on the list including the
    digested mail user, whose MTA then rejects the email for the same reason as
    before.
    5. Repeat steps 3 and 4 about every 8 minutes.

    This loop continues until the system comes to a halt from a full /tmp
    directory. On every iteration the mail message grew a little bigger
    because the last email gets copied on to the reject message.

    There are a few problems here, but I'm not sure which problem is the wrong
    case and which solution I should pursue.


    Problem #1. ccMail changes the headers when it processes the mail.

    Here's the normal headers from a post to mailman (I've stripped the
    Received lines):
    From: Rich Ramos <rich at chi.mti.com>
    To: test at chi.mti.com
    Message-ID: <563517.996585740@[144.86.11.157]>
    X-Mailer: Mulberry/2.1.0b3 (Mac OS X)
    MIME-Version: 1.0
    Content-Type: text/plain; charset=us-ascii; format=flowed
    Content-Transfer-Encoding: 7bit
    Content-Disposition: inline
    Subject: [Test] test to show headers
    Sender: test-admin at chi.mti.com
    Errors-To: test-admin at chi.mti.com
    X-BeenThere: test at chi.mti.com
    X-Mailman-Version: 2.0.3
    Precedence: bulk
    List-Help: <mailto:test-request at chi.mti.com?subject=help>
    List-Post: <mailto:test at chi.mti.com>
    List-Subscribe: <http://chi.mti.com/mailman/listinfo/test>,
    <mailto:test-request at chi.mti.com?subject=subscribe>
    List-Id: <test.chi.mti.com>
    List-Unsubscribe: <http://chi.mti.com/mailman/listinfo/test>,
    <mailto:test-request at chi.mti.com?subject=unsubscribe>
    List-Archive: <http://chi.mti.com/mailman/private/test/>
    Date: Tue, 31 Jul 2001 13:22:20 -0500

    Here's the way the headers get changed by ccmail:
    Message-Id: <0107319966.AA996603967 at ccmgate.mti.com>
    X-Mailer: ccMail Link to SMTP R8.30.00.7
    Date: Tue, 31 Jul 2001 13:22:20 -0700
    From: Rich Ramos <rich at chi.mti.com>
    To: <test at chi.mti.com>
    Subject: [Test] test to show headers
    MIME-Version: 1.0
    Content-Type: multipart/mixed; boundary="simple boundary"

    As you can tell it's quite a bit different. However I'm not totally clear
    that even with the changed headers, that the destination MTA should have
    sent the bounce message back to the list. With the From: and To: headers
    the way they are why didn't the MTA send the bouce back to the From:
    address?

    Problem #2:
    The message was being delivered to a digested user, however the bounces
    happened every few minutes. Why didn't the digest get sent once and then
    not again until the next interval for the digest?

    Doesn't mailman have some mechanism to catch looping posts to a list?

    -Rich
  • John W Baxter at Aug 5, 2001 at 12:22 am

    At 13:47 -0500 7/31/2001, Rich Ramos wrote:
    Problem #2:
    The message was being delivered to a digested user, however the bounces
    happened every few minutes. Why didn't the digest get sent once and then
    not again until the next interval for the digest?
    I haven't seen this part answered. Probably, it is because the problem
    message was larger than the digest size, so that as soon as an instance
    came in the digest was big enough to send.

    --John
    --
    John Baxter jwblist at olympus.net Port Ludlow, WA, USA
  • Rich Ramos at Aug 1, 2001 at 5:44 am
    After some digging I think I have found out that we are running into bug "[
    #231776 ] Digest From address causing mail loop", however ours has some
    twists that I don't think the suggestion in the bug database will fix.

    Also, I have some unanswered questions from this bug:
    1. Why doesn't the parameter 'LIKELY_BOUNCE_SENDERS' prevent this situation
    from happening at all? The MTA sending the email is coming from this
    address: "From: Mail Administrator <postmaster at bellsouth.net>"
    Do I not understand this parameter correctly?

    2. In the situation that is described in the bug report, why don't the
    headers 'Sender:' & 'Errors-To:' get used? What are these headers suppose
    to be used for?

    On top of those questions, in our situation I don't know if just changing
    the 'From' address will help. The ccMail system that I refered to in my
    last email, changes the From address and replaces it with the Reply-to
    address (which it completely drops). Which is why the bounce snowball was
    sent to all users on the dist list because it got changed from
    <list>-request to just <list>. So we would have wound up in the same
    situation even if the From address was <list>-owner. Ugly.

    I have included the headers as the get changed by the ccMail system for
    digest emails. The list is test and the domain is chi.mti.com

    Normal:
    Received: from becks (localhost [127.0.0.1])
    by becks.chi.mti.com (8.8.8/8.8.8) with ESMTP id UAA17934;
    Tue, 31 Jul 2001 20:16:02 -0500 (CDT)
    Date: Tue, 31 Jul 2001 20:16:02 -0500 (CDT)
    Message-Id: <200108010116.UAA17934 at becks.chi.mti.com>
    From: test-request at chi.mti.com
    Subject: Test digest, Vol 1 #5 - 5 msgs
    Reply-to: test at chi.mti.com
    X-Mailer: Mailman v2.0.3
    MIME-version: 1.0
    Content-type: text/plain
    To: test at chi.mti.com
    Sender: test-admin at chi.mti.com
    Errors-To: test-admin at chi.mti.com
    X-BeenThere: test at chi.mti.com
    X-Mailman-Version: 2.0.3
    Precedence: bulk
    List-Help: <mailto:test-request at chi.mti.com?subject=help>
    List-Post: <mailto:test at chi.mti.com>
    List-Subscribe: <http://chi.mti.com/mailman/listinfo/test>,
    <mailto:test-request at chi.mti.com?subject=subscribe>
    List-Id: <test.chi.mti.com>
    List-Unsubscribe: <http://chi.mti.com/mailman/listinfo/test>,
    <mailto:test-request at chi.mti.com?subject=unsubscribe>
    List-Archive: <http://chi.mti.com/mailman/private/test/>


    ccMail:
    Received: from bud.chi.mti.com (root at bud [192.107.118.17])
    by becks.chi.mti.com (8.8.8/8.8.8) with ESMTP id UAA17958
    for <Ramos at chi.mti.com>; Tue, 31 Jul 2001 20:16:14 -0500 (CDT)
    Received: from mtigate.mti.com (mtigate.mti.com [144.86.1.1])
    by bud.chi.mti.com (8.9.3/8.9.3) with ESMTP id UAA18194
    for <Ramos at chi.mti.com>; Tue, 31 Jul 2001 20:16:13 -0500
    From: test at chi.mti.com
    Received: from ccmgate.mti.com (ccmgate.mti.com [144.86.14.157])
    by mtigate.mti.com (Build 101 8.9.3/NT-8.9.3) with SMTP id SAA28830
    for <Ramos at chi.mti.com>; Tue, 31 Jul 2001 18:16:05 -0700
    Received: from POP3 Client by ccmgate.mti.com (ccMail Link to SMTP
    R8.30.00.7)
    id AA996628767; Tue, 31 Jul 2001 18:19:29 -0700
    Message-Id: <0107319966.AA996628767 at ccmgate.mti.com>
    X-Mailer: ccMail Link to SMTP R8.30.00.7
    Date: Tue, 31 Jul 2001 20:16:02 -0700
    To: <test at chi.mti.com>
    Subject: Test digest, Vol 1 #5 - 5 msgs
    MIME-Version: 1.0
    Content-Type: multipart/mixed; boundary="simple boundary"

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postedJul 31, '01 at 6:36p
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