Hmmm, anyway, some basic javascript validation on each field, means they must enter a field, as in the database you have it set up as to not allow blank fields .. then you must validate it somehow ... i normally do it in ASP and send them back with the fields missing in red text .. but here is the javascript way .. this replaces the top of the mailto page .. starting at the very top and ending with the Form tag.

Code:
<html>
<head>
<Script Language="JavaScript">
function Form_Submit() {
	if ((feedback.name.value=='Put your name') ||
		(feedback.name.value=='')) 
	{
		alert("Please Enter Your Name");
		return false;	
	}
   	else if ((feedback.email.value=='Put your email address') ||
		(feedback.email.value=='')) 
	{
		alert("Please Enter Your Email Address");
		return false;	
	}
   	else if ((feedback.subject.value=='Put your subject') ||
		(feedback.subject.value=='')) 
	{
		alert("Please Enter Your Subject");
		return false;	
	}
   	else if ((feedback.comment.value=='Put your comments') ||
		(feedback.comment.value==''))
	{
		alert("Please Enter Your Comments");
		return false;	
	}
   	else { return true; }
}

</script>
</head>

<body>

<form action="feedbacksent.asp" method="post" name="feedback" onSubmit="return Form_Submit();">