Subject: DSN: failed (Mail System Error - Returned Mail)

From: Mailbot for etexusa.com <>
Date: Wed, 30 Mar 2011 03:51:39 -0700

This is a Delivery Status Notification (DSN).

I was unable to deliver your message to
[email-masked].

I said 
  RCPT TO:<[email-masked]>

And they gave me the error;
  553 5.3.0 <[email-masked]>... User unknown