function mailsubmit() {

	if (isEmpty(sendmail.username.value)){
		alert("姓名不能为空");
		return;
	}
	if (isEmpty(sendmail.tel.value)){
		alert("电话不能为空");
		return;
	}
	if (isEmpty(sendmail.addr.value)){
		alert("地址不能为空");
		return;
	}
	if (isEmpty(sendmail.youbian.value)){
		alert("邮编不能为空");
		return;
	}
	if (isEmpty(sendmail.emailaddr.value) || !isEmail(sendmail.emailaddr.value)){
		alert("E-mail无效！");
		return;
	}
	if (isEmpty(sendmail.neirong.value)){
		alert("内容不能为空");
		return;
	}
   
	window.document.sendmail.action = "sendmail.asp";
	window.document.sendmail.submit();   

}