Subject: Returned mail: see transcript for details

From: Mail Delivery Subsystem <[email-masked]>
Date: Wed, 2 Jul 2008 21:09:27 +0200

The original message was received at Wed, 2 Jul 2008 21:09:16 +0200
from [213.234.21.173]

   ----- The following addresses had permanent fatal errors -----
<[email-masked]>
    (reason: 550 5.1.1 User unknown)

   ----- Transcript of session follows -----
... while talking to mail.kleinestaarman.com.:
>>> DATA
<<< 550 5.1.1 User unknown
550 5.1.1 <[email-masked]>... User unknown
<<< 503 5.5.2 Need Rcpt command.