Subject: Returned mail: see transcript for details

From: Mail Delivery Subsystem <[email-masked]>
Date: Thu, 12 Apr 2007 06:38:32 -0500

The original message was received at Thu, 12 Apr 2007 06:38:30 -0500
from localhost.localdomain [127.0.0.1]

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

   ----- Transcript of session follows -----
... while talking to mx1.earthlink.net.:
>>> RCPT To:<[email-masked]>
<<< 550 [email-masked]...User unknown
550 5.1.1 <[email-masked]>... User unknown