The original message was received at Fri, 25 Jan 2008 20:51:39 -0800
from lb.z57.com [209.75.14.120]
----- The following addresses had permanent fatal errors -----
<b@comcast.net>
(reason: 550 5.1.1 Not our Customer)
----- Transcript of session follows -----
... while talking to mx2.comcast.net.:
>>> RCPT To:<b@comcast.net>
<<< 550 5.1.1 Not our Customer
550 5.1.1 <b@comcast.net>... User unknown