In such case, you need to relay off the Exchange server 2007 by allowing application servers.
You have to implement some relay restrictions on the virtual server.
This may only be happening locally, so if you’re in Houston, and can’t send mail thru Go Daddy, give this a shot! To ping a server on Windows 8, hold down the window key and tap the “R” key. Enter “cmd” (without the quotes) then hit enter, and a command prompt will appear.
Go to general tab and check whether FQDN is correct or not.
Go to network tab and check for the details you have entered in the IP addresses.
Among all SMTP reply messages, error 550 is surely the most common.
It generally comes with a side-message like "550 Requested action not taken: mailbox unavailable" or "550 5 2 1 mail from refused spam site".
Now go to Authentication tab and ensure that only ‘Transport Layer Security (TLS)’ is selected there.