Subject: Warning: could not send message for past 4 hours

From: Mail Delivery Subsystem <[email-masked]>
Date: Tue, 28 Oct 2008 03:20:07 +0700

**********************************************
    **      THIS IS A WARNING MESSAGE ONLY      **
    **  YOU DO NOT NEED TO RESEND YOUR MESSAGE  **
    **********************************************

The original message was received at Thu, 23 Oct 2008 08:54:23 +0700
from adsl190-28-184-3.epm.net.co [190.28.184.3]

   ----- Transcript of session follows -----
... while talking to [89.105.145.163]:
>>> DATA
<<< 450 <[email-masked]>: User unknown in local recipient table
<[email-masked]>... Deferred: 450 <[email-masked]>: User unknown in local recipient table
<<< 554 Error: no valid recipients
Warning: message still undelivered after 4 hours
Will keep trying until message is 5 days old