Subject: Returned mail: see transcript for details

From: Mail Delivery Subsystem <[email-masked]>
Date: Mon, 14 Jan 2008 20:58:07 +0100

The original message was received at Mon, 14 Jan 2008 20:58:07 +0100
from localhost.localdomain [127.0.0.1]

   ----- The following addresses had permanent fatal errors -----
<[email-masked]>
    (reason: 550 No such user ([email-masked]))

   ----- Transcript of session follows -----
... while talking to mailfilter1.ifad.org.:
>>> DATA
<<< 550 No such user ([email-masked])
550 5.1.1 <[email-masked]>... User unknown
<<< 503 Bad sequence of commands