Subject: Returned mail: see transcript for details

From: Mail Delivery Subsystem <[email-masked]>
Date: Thu, 4 Sep 2008 02:31:50 +0400 (MSD)

The original message was received at Thu, 4 Sep 2008 02:28:24 +0400 (MSD)
from [190.67.250.10]

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

   ----- Transcript of session follows -----
... while talking to enzyme-e-204a-2.chem.msu.ru.:
>>> RCPT To:<[email-masked]>
<<< 550 User unknown
550 5.1.1 <[email-masked]>... User unknown