On 8/23/2018 9:04 AM, Denis Heidtmann wrote:
> I have no idea how the spammer managed
> to change her reply-to field

It is trivially easy to forge/modify headers except those added by
servers traversed after the message leaves the sending mail transfer
agent.  When reading headers they are in most-recent first order, so
anything after (in reading order) the last (earliest) "Received: from
..." was created by the sender and is untrustworthy in the case of SPAM.
This includes From:, To:, Reply-to:, Date:, Subject:, Sender:, etc.

Here's a sample set of headers showing the breakdown between what is
trustworthy and what is not

> Return-Path: <[email protected]>
> X-Original-To: [[redacted]]
> Delivered-To: [[redacted]]
> X-Greylist: whitelisted by SQLgrey-1.8.0
> DKIM-Filter: OpenDKIM Filter v2.11.0 smtp.[[redacted]] D68E040323
> Received: from acmsmtp02.acm.org (ACMSMTP02.acm.org [64.238.159.79])
>     (using TLSv1.2 with cipher DHE-RSA-AES256-GCM-SHA384 (256/256 bits))
>     (No client certificate requested)
>     by smtp.[[redacted]] (Postfix) with ESMTPS id D68E040323
>     for <[[redacted]]>; Thu, 23 Aug 2018 10:29:48 -0400 (EDT)
> Received: from in-004.mia.mailroute.net
>         by acmsmtp02.acm.org (ACM Email Forwarding Service) with ESMTP id 
> 2201808231029476520
>         for <[[redacted]]>; Thu, 23 Aug 2018 10:29:47 -0400
> Received: from localhost (004.mia.mailroute.net [127.0.0.1])
>     by in-004.mia.mailroute.net (Postfix) with ESMTP id 41x6Hq6sptzHp7M
>     for <[[redacted]]>; Thu, 23 Aug 2018 14:29:43 +0000 (UTC)
> X-Virus-Scanned: by MailRoute
> X-Spam-Flag: NO
> X-Spam-Score: 2.721
> X-Spam-Level: **
> X-Spam-Status: No, score=2.721 tagged_above=-9999 tests=[BAYES_00=-1.9,
>     BTC_ENCODED_SUB=0.1, KAM_LAZY_DOMAIN_SECURITY=1, KAM_LINKBAIT=2.5,
>     MISSING_HEADERS=1.021] autolearn=no autolearn_force=no
> X-Spam-ASN:  
> X-Spam-Language: 
> X-Spam-Relay-Countries: US ** US
> Received: from in-004.mia.mailroute.net ([199.89.3.7])
>     by localhost (004.mia [127.0.0.1]) (mroute_mailscanner, port 10024)
>     with LMTP id qiKHiQZpuG_1; Thu, 23 Aug 2018 14:29:30 +0000 (UTC)
> Received: from utm.njea.org (utm.njea.org [208.84.250.36])
>     (using TLSv1 with cipher ECDHE-RSA-AES256-SHA (256/256 bits))
>     (No client certificate requested)
>     by in-004.mia.mailroute.net (Postfix) with ESMTPS id 41x6HX19cLzHp7n;
>     Thu, 23 Aug 2018 14:29:27 +0000 (UTC)
>     
   ******** Above here generated by servers outside of spammer's control
********

   ************** Below here MAY be forged with some difficulty
****************
> 
> Received: from SP50.njea.org ([169.254.2.7]) by SP50.njea.org
>  ([192.168.40.50]) with mapi id 14.03.0248.002; Thu, 23 Aug 2018 10:29:13
>  -0400

   ******************* Below here can be trivially forged
*************************

> From: Renee Ahern <[email protected]>
> Subject: Microsoft Outlook
> Thread-Topic: Microsoft Outlook
> Thread-Index: AdQ67am/r3zLggSIQzGDwsaKZ3eSSg==
> Date: Thu, 23 Aug 2018 14:29:13 +0000
> Message-ID: <[email protected]>
> Accept-Language: en-US
> Content-Language: en-US
> X-MS-Has-Attach:
> X-MS-TNEF-Correlator:
> x-originating-ip: [5.62.47.11]
> Content-Type: text/plain; charset="iso-8859-1"
> Content-Transfer-Encoding: quoted-printable
> MIME-Version: 1.0


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