SpamCop doesn't parse routing info correctly

I'm running into an odd problem where SpamCop fails to correctly identify
the source of an e-mail.

Here's the situation: the spammer in question is a crazy guy who has been
mass mailing his incoherent rants to everyone in his address book for
years.  He always uses a Yahoo! Mail account, which he logs into at some
public access library terminal at the University of Arizona.  (He has
admitted as much.)  When I forward to SpamCop an offending e-mail that I
received at my personal account ([email protected]), SpamCop
correctly identifies the source as an IP at the University of Arizona.  My
employer ([email protected]) is also on the spammer's mailing list. 
However, when *they* (or I) send their copy of the very same e-mail to
SpamCop, it fails to identify the source as the University of Arizona. 
This is very strange, since both copies of the e-mail contain the same
Received header giving a U of A IP (128.196.165.21 =
PUB-E3.AHSL.Arizona.EDU):

Received: from [128.196.165.21] by web35715.mail.mud.yahoo.com via HTTP;
Wed, 12 Apr 2006 16:07:39 PDT

Both our domains, nothingisreal.com and worldsocialism.org, are hosted by
DreamHost.  The only major difference in our setup is that I use fetchmail
to download my mail via POP3 from mail.nothingisreal.com and deliver it to
a local mail server, whereas my employer checks mail via IMAP on
mail.worldsocialism.org.

I reproduce here the headers of the e-mail in question in case anyone wants
to check with SpamCop themselves.  (SpamCop seems to allow submission of
headers without a body for parsing purposes.)

Here is the version I received which SpamCop correctly parses. Tracking
URL:
<http://www.spamcop.net/sc?id=z919791081z249ddd61c3743f1bde510714fd343b2az>

Return-Path: <[email protected]>
X-Original-To: psy@localhost
Delivered-To: [email protected]
Received: from localhost (localhost [127.0.0.1])
        by polecat.worldsocialism.org (Postfix) with ESMTP id 04EA6903D9
        for <psy@localhost>; Thu, 13 Apr 2006 00:15:50 +0100 (BST)
X-Original-To: [email protected]
Delivered-To: [email protected]
Received: from mail.nothingisreal.com [208.97.132.24]
        by localhost with POP3 (fetchmail-6.2.5)
        for psy@localhost (single-drop); Thu, 13 Apr 2006 00:15:50 +0100 (BST)
Received: from web35715.mail.mud.yahoo.com (web35715.mail.mud.yahoo.com
[66.163.179.169])
        by randymail-mx2.dreamhost.com (Postfix) with SMTP id B492913B3E0
        for <[email protected]>; Wed, 12 Apr 2006 16:07:40 -0700 (PDT)
Received: (qmail 4652 invoked by uid 60001); 12 Apr 2006 23:07:39 -0000
DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws;
  s=s1024; d=yahoo.com;
 
h=Message-ID:Received:Date:From:Subject:To:MIME-Version:Content-Type:Content-Transfer-Encoding;
 
b=rb80uMH7Kp4m/VGyzMC0i7vOkVAkMZ4UCxjNcwT5NIAsa2OhjLIOQiGfDr5u3GeGDVNiJh5gP4IrizKokJRF8JJ22pQ9LRZonUf2+SImTvUXUDFs1tQ9LHS8Y5VA/E/nM4GsuqMwaKflXpB9gec0jEg2CTyAnB6DWWQPf8/MIZw=  ;
Message-ID: <[email protected]>
Received: from [128.196.165.21] by web35715.mail.mud.yahoo.com via HTTP;
Wed, 12 Apr 2006 16:07:39 PDT
Date: Wed, 12 Apr 2006 16:07:39 -0700 (PDT)
From: L-ightist Economist <[email protected]>
Subject: Fwd: Re: JB:  Emails Violated and Erased by Unknown; Cannot
Respond Immediately...EXPEL ME

Here is the version my employer received which SpamCop doesn't correctly
parse.  Tracking URL:
<http://www.spamcop.net/sc?id=z919793041z85093855a4505837202f64fc298ebaa6z>

Return-Path: <[email protected]>
X-Original-To: [email protected]
Delivered-To: [email protected]
Received: from enforcer.dreamhost.com (enforcer.dreamhost.com
[66.33.220.4])
        by randymail-mx1.dreamhost.com (Postfix) with ESMTP id D18C434339
        for <[email protected]>; Wed, 12 Apr 2006 16:07:47 -0700 (PDT)
Received: from localhost (localhost [127.0.0.1])
        by enforcer.dreamhost.com (Postfix) with ESMTP id AE0C017D010
        for <[email protected]>; Wed, 12 Apr 2006 16:07:47 -0700 (PDT)
Received: from enforcer.dreamhost.com ([127.0.0.1])
        by localhost (enforcer [127.0.0.1]) (amavisd-new, port 10024)
        with ESMTP id 04356-06 for <[email protected]>;
        Wed, 12 Apr 2006 16:07:46 -0700 (PDT)
Received: from hesl01uker.he.local (smtpout.btconnect.com [213.123.26.90])
        by enforcer.dreamhost.com (Postfix) with ESMTP id ED6DF17D025
        for <[email protected]>; Wed, 12 Apr 2006 16:07:45 -0700 (PDT)
Received: from c2bthimr02.btconnect.com ([194.73.73.202]) by
hesl01uker.he.local with Microsoft SMTPSVC(6.0.3790.211);
         Thu, 13 Apr 2006 00:07:42 +0100
Received: from web35715.mail.mud.yahoo.com (web35715.mail.mud.yahoo.com
[66.163.179.169])
        by c2bthimr02.btconnect.com (MOS 3.5.9-GR)
        with SMTP id FRP26850;
        Thu, 13 Apr 2006 00:06:54 +0100 (BST)
Received: (qmail 4652 invoked by uid 60001); 12 Apr 2006 23:07:39 -0000
DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws;
  s=s1024; d=yahoo.com;
 
h=Message-ID:Received:Date:From:Subject:To:MIME-Version:Content-Type:Content-Transfer-Encoding;
 
b=rb80uMH7Kp4m/VGyzMC0i7vOkVAkMZ4UCxjNcwT5NIAsa2OhjLIOQiGfDr5u3GeGDVNiJh5gP4IrizKokJRF8JJ22pQ9LRZonUf2+SImTvUXUDFs1tQ9LHS8Y5VA/E/nM4GsuqMwaKflXpB9gec0jEg2CTyAnB6DWWQPf8/MIZw=  ;
Message-ID: <[email protected]>
Received: from [128.196.165.21] by web35715.mail.mud.yahoo.com via HTTP;
Wed, 12 Apr 2006 16:07:39 PDT
Date: Wed, 12 Apr 2006 16:07:39 -0700 (PDT)
From: L-ightist Economist <[email protected]>
Subject: Fwd: Re: JB:  Emails Violated and Erased by Unknown; Cannot
Respond Immediately...EXPEL ME

-- 
   _
  _V.-o  Tristan Miller [en,(fr,de,ia)]  ><  Space is limited
 / |`-'  -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=  <>  In a haiku, so it's hard
(7_\\    http://www.nothingisreal.com/   ><  To finish what you