Subject: Returned mail: see transcript for details

From: Mail Delivery Subsystem <[email-masked]>
Date: Mon, 15 Oct 2007 13:52:01 +0200

The original message was received at Mon, 15 Oct 2007 13:51:58 +0200
from [59.93.19.250]

   ----- The following addresses had permanent fatal errors -----
<[email-masked]>
    (reason: 550 5.1.1 Mailbox <[email-masked]> does not exist)

   ----- Transcript of session follows -----
... while talking to mail.nobuko.net.:
>>> DATA
<<< 550 5.1.1 Mailbox <[email-masked]> does not exist
550 5.1.1 <[email-masked]>... User unknown