System having an error to send automatic e-mail to users

“on the site http://www.thepassiontest.com, after the user fill in the questionnaire, write his name, e-mail, he hits the button of “”click here to receive your passion profile assessment””. The profile assessment must be sent to user. But it does not send the profile assessment  to user´s email address.
how can I solve this problem?
The staff in GoDaddy says:
find from File Manager that which plugin is used. after learning which plugin is used, go to wordpress forum and ask help.
Php function should be used to send smtp e-mail.
This is an extremely important and urgent issue. if you can help I will be very happy and glad.”