mailer error: The following form address failed info@khabarbin.com : Called Mail() without being con

Hi;
I have installed and created a newsletter in my site then I tried to send a test one out but I got this error message:

mailer error: The following form address failed info@khabarbin.com : Called Mail() without being connected

My email is connected and my SMTP is set as it should. Please let me know where am I going wrong so I can get this plugin to work.
Best Regards
Bobby