Subject: Returned mail: see transcript for details

From: Mail Delivery Subsystem <[email-masked]>
Date: Mon, 22 Sep 2008 21:00:01 -0500 (CDT)

The original message was received at Mon, 22 Sep 2008 20:59:59 -0500 (CDT)
from [59.174.55.122]

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

   ----- Transcript of session follows -----
... while talking to clortho.acm.uiuc.edu.:
>>> DATA
<<< 550 unknown user
550 5.1.1 <[email-masked]>... User unknown
<<< 503 valid RCPT command must precede DATA