Maybe this will help your investigation:
dublinw@microsoft.com
on 18/11/2008 2:31 PM
The e-mail system was unable to
deliver the message, but did not report a specific reason. Check the address and try again. If it still fails, contact your system
administrator.
< mail18-va3-R.bigfish.com
#5.0.0 X-Postfix; host winse-6216-mail3.customer.frontbridge.com[205.248.106.32]
said: 550 5.1.1 User unknown (in reply
to RCPT TO command)>