Who is your host?
In the Universal Email Settings, what have you entered for the From address? Many hosts will require that the from address be a valid email address for your domain. In the advanced FRom section, there is an option to include the from address as an extra parameter, some hosts require this option to be set.
What did you enter for the SMTP Server address? some hosts will work if this is left blank, others require that the SMTP Server address be entered.