Subject: Returned mail: see transcript for details

From: Mail Delivery Subsystem <[email-masked]>
Date: Thu, 19 Oct 2006 01:11:22 -0400

The original message was received at Thu, 19 Oct 2006 01:11:21 -0400
from [86.106.178.164]

   ----- The following addresses had permanent fatal errors -----
<[email-masked]>
    (reason: 553 5.3.0 <[email-masked]>... Relay Validation Failed - User Not Found)

   ----- Transcript of session follows -----
... while talking to localhost:
>>> DATA
<<< 553 5.3.0 <[email-masked]>... Relay Validation Failed - User Not Found
550 5.1.1 <[email-masked]>... User unknown
<<< 503 5.0.0 Need RCPT (recipient)