String.prototype.isValidEmail = function(){
	return !!this.match(/^([a-zA-Z0-9]{1}([a-zA-Z0-9\.\-\_]*)[a-zA-Z0-9]{1})@([a-zA-Z0-9]{1}([a-zA-Z0-9\.\-\_]*)[a-zA-Z0-9]{1})\.([a-zA-Z]{2,4})$/)
}
function validateForm() {
	if (document.f.name.value=="") {
		alert("Please enter your name.");
		return false;
	} else if (!document.f.email.value.isValidEmail()) {
		alert("Please enter a valid email address.");
		return false;
	} else if (!document.f.message.value) {
		alert("Please enter a message.");
		return false;
	} 
}