function checkForm (monForm) {

   if (monForm.surname.value == "") {
     alert ('Please enter your surname.');
	 monForm.surname.focus();
     return false;
   }
      
   if (monForm.mail.value == "") {
     alert ('Please enter your email address.');
	 monForm.mail.focus();
     return false;
   }
   
	var str=monForm.mail.value
	var filter=/^([a-zA-Z0-9_\-\.]+)@[a-zA-Z0-9_\-.]+((\.[a-zA-Z]{3}\.[a-zA-Z]{2}$)|(\.[a-zA-Z]{3}$)|(\.[a-zA-Z]{2}\.[a-zA-Z]{2}$))$/i
	if (!filter.test(str)) {
			alert("Please input a valid email address.")
			monForm.mail.focus();
			return false;
	}

	if (monForm.theme.value == "") {
     alert ('Please choose a theme.');
	 monForm.theme.focus();
     return false;
   }

   if(monForm.message.value == "" ){
     monForm.message.value = " ";
   }

   return true;
}