function isEmailValid(email) {
    var pattern = /^([a-zA-Z0-9_'+*$%\^&!\.\-])+\@(([a-zA-Z0-9\-])+\.)+([a-zA-Z0-9:]{2,4})+$/;
    if (!pattern.test(email)) {
        return false;
    } else {
        return true;
    }
}

function chCF(F) {
	var e=''; 
	
    if (!F.name.value.length) e+="Please enter your name\n"; 
	if (!F.email.value.length) {
        e+="Please enter your email\n";
    } else if (!isEmailValid(F.email.value)) {
        e+="Email address is not valid\n";
    }
    if (!F.comments.value.length) e+="Comments and Questions field is required\n";
	
	if (e.length) { 
		alert(e); 
		return false;
	}
	return true;
}