function checkmail()
{
	if (document.forms['form1'].elements['mail'].value == ""){
		alert("Please enter your email address");
		return false;
	}
	var filter  = /^([a-zA-Z0-9_\.\-])+\@(([a-zA-Z0-9\-])+\.)+([a-zA-Z0-9]{2,4})+$/;
	if (!filter.test(document.forms['form1'].elements['mail'].value)){
		alert ("• Please enter your valid email address");
		return false;
	}	
	document.forms['form1'].submit();
}