function check_add()
{
	var val=document.form_add
	
	if (val.txtProName.value == "")
    {
        alert("Product name cannot be empty, please input!");
		val.txtProName.focus();
        return (false);
    }
	
	if (val.mail_title.value == "")
    {
        alert("Title cannot be empty, please input!");
		val.mail_title.focus();
        return (false);
     }
	 
	if (val.mail_content.value == "")
    {
        alert("Content cannot be empty, please input!");
		val.mail_content.focus();
        return (false);
     }	
	
	if (val.sender_name.value == "")
    {
        alert("Name cannot be empty, please input!");
		val.sender_name.focus();
        return (false);
     }
	
	//校验用户姓名：只能输入1-30个以字母开头的字串 
	var patrn=/^[a-zA-Z]{1,30}$/;
	if(!patrn.exec(val.sender_name.value))
	{
        alert('Please input your real name');
		val.sender_name.focus();
		val.sender_name.select();
        return false;
     } 
	
	if (val.sender_mail.value == "")
    {
        alert("E-mail cannot be empty, please enter!");
		val.sender_mail.focus();
        return (false);
     }
     var filter=/^\s*([A-Za-z0-9_-]+(\.\w+)*@(\w+\.)+\w{2,3})\s*$/;
     if (!filter.test(val.sender_mail.value)) 
	 { 
         alert("E-mail format error!"); 
         val.sender_mail.focus();
         val.sender_mail.select();
         return (false); 
     } 
	
	if (val.sender_tel.value == "")
    {
        alert("Phone number cannot be empty, please enter!");
		val.sender_tel.focus();
        return (false);
     }
	 
	//校验普通电话、传真号码：可以“+”开头，除数字外，可含有“-”
	var patrn=/^[+]{0,1}(\d){1,3}[ ]?([-]?((\d)|[ ]){1,12})+$/; 
    if (!patrn.exec(val.sender_tel.value)) 
	{ 
        alert("The Phone number format mistake!"); 
        val.sender_tel.focus();
        val.sender_tel.select();
        return (false); 
    } 
	
	if (val.sender_add.value == "")
    {
        alert("Address cannot be empty, please enter!");
		val.sender_add.focus();
        return (false);
    }
		   
}