function checkForm()
{
   form_ok = true;

   if(      document.emailFeedback.firstName.value  == "" ) 
   { 
      alert( "Please fill in your first name."  ); 
      document.emailFeedback.firstName.focus();
      form_ok=false; 
   }
   else if( document.emailFeedback.lastName.value  == "" ) 
   { 
      alert( "Please fill in your last name."   ); 
      document.emailFeedback.lastName.focus();
      form_ok=false; 
   }
   else if( document.emailFeedback.senderEmail.value     == "" ) 
   { 
      alert( "Please enter your email address." ); 
      document.emailFeedback.senderEmail.focus();
      form_ok=false; 
   }
   else if( document.emailFeedback.subject.value   == "" ) 
   { 
      alert( "Please enter a subject."          ); 
      document.emailFeedback.subject.focus();
      form_ok=false; 
   }
   else if( document.emailFeedback.emailText.value == "" ) 
   { 
      alert( "Please enter some email text."    ); 
      document.emailFeedback.emailText.focus();
      form_ok=false; 
   }
   else if( document.emailFeedback.emailSent.value == "true" )
   {
      alert( "You've already submitted this email.\n\nThis form will now reset itself so that you may send another if you choose." );
      document.emailFeedback.reset();
      form_ok=false
   }

   document.emailFeedback.emailSent.value = "true"
   return form_ok;
}