• User B (sitting at the next desk to user A) sends Internet email to an outside party with a cc to User A who receives it by Notes mail immediately. (1)
  
  
• Said outside party collects email by POP3 fetch (2), destroying SMTP envelope (RCPT TO:<intended_recpient@remote_domain>) (3).
  
  
• So POP3 fetching software infers two new forward envelopes from the RFC2822 headers. One is the correct one. The other is... User A (4).
  
  
• Remote system sends a copy of the message to User A "from" User B (MAIL FROM:<User_B@my_domain>) (5).
  
  
• Because we reject any Internet email that says it is from a sender at our local domain (6), a DSN (7) is generated at the remote end (MAIL FROM:<>) and it comes back to User B telling him that the mail he sent to User A (remember, User A already has his copy) could not be delivered because it was rejected for policy reasons.

I give up.

This message was created automatically by mail delivery software (Exim).

A message that you sent could not be delivered to one or more of its recipients. This is a permanent error. The following address(es) failed: (7)

User_A@my_domain
SMTP error from remote mailer after MAIL FROM:<User_B@my_domain> SIZE=10386:
host myhost [a.b.c.d]: 554 Mail from User_B@my_domain rejected for policy reasons. (6)

------ This is a copy of the message, including all the headers. ------

Return-path: <User_B@my_domain> (5)
Received: from remotehost ([w.x.y.z] helo=remotehost)
by isp_relay with esmtp (Exim 3.35 #1)
id 1AnhAo-000KdG-0U
for User_A@my_domain; Mon, 02 Feb 2004 16:43:47 +0000 (4)
Received: from remotehost ([192.168.1.3]) by remotehost with Microsoft SMTPSVC(5.0.2195.2966);
Mon, 2 Feb 2004 16:34:15 +0000
Received: by remotehost (Microsoft Connector for POP3 Mailboxes 5.00.2195) with SMTP (Global POP3 Download)
id MSG02022004-163043-2258.MMD@remote_domain; Mon, 2 Feb 2004 16:30:43 -0000 (2)
Received: from isp_mailcore by mailstore
for intended_recipient@remote_domain (3)id 1AnghJ-0002Xh-5p;
Mon, 02 Feb 2004 16:13:17 +0000
Received: from [w.x.y.z] (helo=isp_relay)
by isp_mailcore with esmtp id 1AnghJ-0002Xh-5p
for intended_recipient@remote_domain (3); Mon, 02 Feb 2004 16:13:17 +0000
Received: from [a.b.c.d] (helo=myhost)
by isp_relay with esmtp id 1AnggC-0006DV-LP
for intended_recipient@remote_domain (3); Mon, 02 Feb 2004 16:12:08 +0000
To: intended_recipient@remote_domain (1)
Cc: User A <User_A@my_domain> (1)
Subject: Re: Remittance
MIME-Version: 1.0
X-Mailer: Lotus Notes Release 5.0.8 June 18, 2001
Message-ID: <OFBC6F0A8D.5C284142-ON80256E2E.0058AD5D@my_domain>
From: User B <User_B@my_domain>
Date: Mon, 2 Feb 2004 16:10:18 +0000
X-MIMETrack: Serialize by Router on Myhost/my_domain(Release 6.5.1|January 21, 2004) at 02/02/2004 16:12:08,
Serialize complete at 02/02/2004 16:12:08
Content-Type: multipart/related; boundary="=_related 0058E28C80256E2E_="
X-OriginalArrivalTime: 02 Feb 2004 16:34:15.0765 (UTC) FILETIME=[65C55850:01C3E9AA]

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