Subject: Returned mail: see transcript for details

From: Mail Delivery Subsystem <[email-masked]>
Date: Fri, 22 Aug 2008 06:03:46 +0300 (EEST)

The original message was received at Fri, 22 Aug 2008 06:03:10 +0300 (EEST)
from [72.22.144.105]

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

   ----- Transcript of session follows -----
... while talking to relay.ukrfa.kharkov.ua.:
>>> DATA
<<< 550 5.1.1 User unknown
550 5.1.1 <[email-masked]>... User unknown
<<< 503 5.5.2 Need Rcpt command.