function checkmail(){
	var mail = document.mailform.mail.value;
	if(!(/^[a-z0-9]([a-z0-9]*[-_.]?[a-z0-9]+)*@([a-z0-9]*[-_.]?[a-z0-9]+)+[\.][a-z]{2,3}([\.][a-z]{2})?$/.test(mail))){
		alert("请输入正确的Email地址");
		document.mailform.mail.focus();
		return false;
	}
}

function checkcode(){
	var imgcode = document.mailform.imgcode.value;
	if(imgcode.length!=4){
		alert("请输入4位验证码");
		document.mailform.imgcode.focus();
		return false;
	}
}