function submit_contactform() {

   	//sender name field is not blank
	if(document.contactus.name.value == "") {
	        alert("You have to tell us your name.");
	        return false;
	}
	if(document.contactus.email.value == "") {
	        alert("You have to tell us your email address.");
	        return false;
	}
	
return true;
}//end function submit form