This is the error message I get, so I don't think it's the server:
The recipient's e-mail address was not found in the recipient's e-mail system. Microsoft Exchange will not try to redeliver this message for you. Please check the e-mail address and try resending this message, or provide the following diagnostic text to your
system administrator.
The following organization rejected your message: acdri.com.
_______________________________
Sent by Microsoft Exchange Server 2007
**How do you do a private send/close? I already tried turning off the user notifications and then closing, but it still came through.