function validate_form() {
	
var f = document.form1;
	if (f.name.value == "") {
		alert("Please enter your name.");
		f.name.focus();
		return false;
	}

	if (f.email.value == "") {
	    alert("Please enter your email address.");
	    f.email.focus();
	    return false;

	} else if (f.email.value.indexOf(".") != -1) {
        
        var afterdot = f.email.value.substring(f.email.value.lastIndexOf(".") + 1);
        if ((f.email.value.indexOf("@") == -1) || (afterdot.length > 4)) {
            alert("Please enter a valid email address");
	        f.email.focus();
	        return false;
	    }

    } else {
        alert("Please enter a valid email address");
	    f.email.focus();
        return false;
    }
	
	if (f.comments.value == "") {
	    alert("Please provide a message.");
	    f.comments.focus();
    	return false;
	} 
	
	f.submit();
}