The original message was received at Sun, 16 Mar 2008 10:45:12 -0700
from lb.z57.com [209.75.14.120]
----- The following addresses had permanent fatal errors -----
<dnh@a.com>
(reason: 550 Host unknown)
----- Transcript of session follows -----
550 5.1.2 <dnh@a.com>... Host unknown (Name server: a.com: host not found)