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List:       tmda-users
Subject:    Bounced confirm messages don't generate bounce messages?
From:       "Todd A. Jacobs" <nospam () codegnome ! org>
Date:       2008-06-04 3:01:56
Message-ID: 20080604030156.GB29038 () penguin ! codegnome ! org
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Okay, a quick look at rfc-ignorant.org shows that Charter is
deliberately violating RFC 1891. So much for that. :)

However, this problem took me months to uncover because it wasn't
obvious that Charter was violating the RFC because (in my capacity as a
user) I never knew that challenges were being bounced. Here's a test I
ran today, to show what I'm talking about.

    # Procmail log
    procmail: Executing "/usr/local/tmda-1.1.8/bin/tmda-filter"
    procmail: [571] Tue Jun  3 19:38:41 2008
    procmail: Assigning "LASTFOLDER=/usr/local/tmda-1.1.8/bin/tmda-filter"
    From tjacobs@example.com  Tue Jun  3 19:38:39 2008
     Subject: Test again
      Folder: /usr/local/tmda-1.1.8/bin/tmda-filter 

    # TMDA in.log
    Date: Tue, 03 Jun 2008 19:38:41 -0700
    From: Private Citizen <tjacobs@example.com>
      To: tjacobs@codegnome.org
    Subj: Test again
    Actn: CONFIRM action_incoming                                           (1549)

    Date: Tue, 03 Jun 2008 19:38:41 -0700
    From: Private Citizen <tjacobs@example.com>
      To: tjacobs@codegnome.org
    Subj: Test again
    Actn: CONFIRM pending 1212547120.583                                    (1549)

    # Postfix log
    Jun  3 19:38:41 penguin postfix/pickup[491]: D576F37CAB: uid=1000 from=<>
    Jun  3 19:38:41 penguin postfix/cleanup[569]: D576F37CAB: \
                message-id=<1212547121.583.TMDA@penguin.codegnome.org>
    Jun  3 19:38:41 penguin postfix/qmgr[3104]: D576F37CAB: from=<>, size=3325, \
                nrcpt=1 (queue active)
    Jun  3 19:38:43 penguin postfix/smtp[588]: D576F37CAB: to=<tjacobs@example.com>, \
relay=smtp.charter.net[209.225.8.224]:25, delay=1.7, delays=0.02/0.02/1.2/0.46, \
dsn=5.0.0, status=bounced (host smtp.charter.net[209.225.8.224] said: 550 relaying \
                mail to hotmail.com is not allowed (in reply to RCPT TO command))
    Jun  3 19:38:43 penguin postfix/qmgr[3104]: D576F37CAB: removed

The point I'm making is that the bounces generated by Charter aren't
identifiable to the user as such, because no bounce message is delivered
back to the user or (as far as I can tell) back to tmda. This is
probably desirable behavior in *most* cases, in that you don't want to
know every time a forged address is bounced, but it gives no indication
at all that the challenges aren't even being sent.

My guess is that when TMDA injects a message with a null envelope,
postfix doesn't know to return the bounce from Charter to me. And so,
the problem goes undiscovered until some clever postmaster notices
(hopefully faster than I did) that their ISP is flouting the RFCs.

Whatever the reason, I guess the question is whether it's possible for
TMDA to detect this condition, or whether the very nature of sending
challenges with null envelopes makes this impossible.

-- 
"Oh, look: rocks!"
	-- Doctor Who, "Destiny of the Daleks"
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