Hello,
it seems to me that you haven't allowed the host/network to send email. (None is allowed by default).
To give permission, to your host/network you need firstly to create a object which contains the host network.
Then, you must go to Mail->General and click in the 'settings' tab. There you will find a section called 'Relay policy for objects', move your object to the allowed column and save the changes.
Cheers,
Javier