[...]
If it had been bounced, that would be a different thing. In that case, the mail would have been accepted, a new mail created and this new mail sent to the possibly forged sender.
Carlos was right in his observation, that's exactly what's happened here.
See the following lines from the bounce message:
Reporting-MTA: dns; mxa02.ch.as12513.net
X-Postfix-Queue-ID: C86F4D4444
X-Postfix-Sender: rfc822;
suse-security-return-26706-suse=karsites.net@suse.com
Arrival-Date: Wed, 22 Mar 2006 03:55:38 +0000 (GMT)
Final-Recipient: rfc822; karsites@kar.eclipse.co.uk
Action: failed
Status: 5.0.0
Diagnostic-Code: X-Postfix; host 127.0.0.1[127.0.0.1] said: 550 5.7.1 Message
content rejected, UBE, id=32402-01-62 (in reply to end of DATA command)
--C86F4D4444.1142999739/mxa02.ch.as12513.net
Content-Description: Undelivered Message
Content-Type: message/rfc822
Received: from fwd01.ch.as12513.net (fwd01.ch.as12513.net [82.153.252.42])
by mxa02.ch.as12513.net (Postfix) with ESMTP id C86F4D4444
for