Contact form un aiuto per controllo campi e antispam!

[Mas245]

io ho fatto così la prima parte fa il controllo se l'email è corretta del tipo nome@sito.ext e se i campi sono stati scritti tutti

function is_email($email_to_test)
    {
        $re  = "^([a-zA-Z0-9])+([\.a-zA-Z0-9_-])*@([a-zA-Z0-9_-])";
        $re .= "+(\.[a-zA-Z0-9_-]+)*\.([a-zA-Z]{2,6})$";
        if (ereg($re, $email_to_test))
        {
            return TRUE;
        }
        else
        {
            return FALSE;
        }
    }

$error = array();
$good = array();
$name = trim($_POST['name']);
$email = trim($_POST['email']);
$subject = $_POST['subject'];
$comments = $_POST['comments'];
if(isset($_POST['submit'])){
    if($name == ""){
    $error[0] = "Name is Required";
    
    
    }
    if($email == "" or (is_email("$email") != TRUE)){
        $error[1] = "Please Insert Valid Email";
        
    }
    if($subject  == ""){
        $error[3] = "Please Insert a Subject";
        
        }
    if($comments  == ""){
        $error[4] = "Please Leave a Comments";
    
}
if(!$error){
$to = "myemail@email.com";
$headers = "From: ".$name." <".$email.">\r\n";
$headers .= "Reply-To: ".$email."\r\n";
$headers .= "Return-Path: ".$email."\r\n";
$headers .= "Content-Type: text/html; charset=ISO-8859-1\r\n";
if(mail($to, $name, $comments, $headers)) {
    $good[0] = "Message Send";
}else{
    $error[5] = "Error!! Please Resend ";
}
}
}
?> 

ora ad ogni input del form non compilato correttamente faccio uscire l'errore

<form action="contact.php" method="POST" id="form-box">
                    <fieldset>
                        <legend class="n1">Your contact information</legend>
                            <label>[b]Name:[/b]</label>(required)

                                <input type="text" name="name" value=""  /><?php echo $error[0]; ?>
                
                                <label>[b]E-mail:[/b]</label>(required)

                                <input type="text" name="email" value="" /><?php echo $error[1]; ?>

                                <label>[b]Subject:[/b]</label>(required)

                                <input type="text" name="subject" value="" /><?php echo $error[3]; ?>

                                

                    </fieldset>
                    <fieldset>
                        <legend class="n1">Your message</legend>
                            <label>[b]Message:[/b]</label>(required)<?php echo $error[4]; ?>

                                <textarea name="comments" rows="7" cols="50" ></textarea>
                                

                                <input class="button" name="submit" type="submit" value="Send" /><?php echo $error[5]; ?><?php echo $good[0]; ?>
                    </fieldset>
                </form>

spero di esserti stato di aiuto