Upload multiplo con invio allegati per email

[Cosina]

Buongiorno di nuovo. Il mio secondo form (riferimento post precedente) invia gli allegati direttamente per email. L'aiuto che mi serve è sempre per poter caricare più file con un unico campo di input. Ecco il codice che utilizzo e che permette l'upload di un solo file alla volta. Grazie mille ancora per l'aiuto.

<form class="form-contact" action="upload.php" method="post" enctype="multipart/form-data">
            <p><label>Full name:</label>
            <br><input class="field" type="text" name="name" required /></p>
            <p><label>E-mail:
            <br></label><input class="field" type="email" name="email" required /></p>
            <p><label>Message: </label>
            <br><textarea name="message" required ></textarea></p>
            <p><label>File:</label>
               <input type="file" name="attachFile" />
            </p>
            <p class="p-captcha">Antispam: <br><img class="img-captcha" id="captcha" src="./captcha.php" alt="captcha"/>
               <a class="a-captcha" onclick="reload()"> &orarr;</a><br>
               <label><span class="span-captcha">Type the numbers</span></label><br>
               <input type="text" name="captcha" />
            </p>
            <div class="button-container">
               <input class="contact-button" type="reset" value="Reset">
               <input class="contact-button" type="submit" value="Send">
            </div>
         </form>

PHP:

session_start();
if ($_POST['captcha'] != $_SESSION['captcha']) {
    echo '<script type="text/javascript">alert("Captcha errato / Incorrect captcha");window.history.go(-1);</script>';
    die();
}

//Defining mail settings
$to = "mail@mail";
$subject= "Invio di file / Sending files";
$todayis = date("l, F j, Y, g:i a") ;

$name = $_POST['name'];
$email = $_POST['email'];
$message = ($_POST['message']);

$message = "
Date: $todayis
Name: $name
Email: $email
Message: $message
";


  $mime_boundary="==Multipart_Boundary_x".md5(mt_rand())."x";
         $headers = "From: $email\r\n" .
         "MIME-Version: 1.0\r\n" .
            "Content-Type: multipart/mixed;\r\n" .
            " boundary=\"{$mime_boundary}\"";
         $message = "This is a multi-part message in MIME format.\n\n" .
            "--{$mime_boundary}\n" .
            // impostare il set di caratteri come nella casella di posta
            "Content-Type: text/plain; charset=\"utf-8\"\n" .
            //...............................................
            "Content-Transfer-Encoding: 7bit\n\n" .
         $message . "\n\n";

         foreach($_FILES as $userfile)
         {
            $tmp_name = $userfile['tmp_name'];
            $type = $userfile['type'];
            $name = $userfile['name'];
            $size = $userfile['size'];
            if (file_exists($tmp_name))
            {
               if(is_uploaded_file($tmp_name))
               {
                  $file = fopen($tmp_name,'rb');
                  $data = fread($file,filesize($tmp_name));
                  fclose($file);
                  $data = chunk_split(base64_encode($data));
               }
               $message .= "--{$mime_boundary}\n" .
                  "Content-Type: {$type};\n" .
                  " name=\"{$name}\"\n" .
                  "Content-Disposition: attachment;\n" .
                  " filename=\"{$fileatt_name}\"\n" .
                  "Content-Transfer-Encoding: base64\n\n" .
               $data . "\n\n";
            }
         }
         $message.="--{$mime_boundary}--\n";         
        
// Check filesize
if($_FILES['file_upload']['size'] > 500000){
    //die('File uploaded exceeds maximum upload size.');
    echo '<script type="text/javascript">alert("Il file supera le dimensioni consentite");window.history.go(-1);</script>';
}       
        
if (mail($to, $subject, $message, $headers))
   echo '<script type="text/javascript">alert("Successo!");window.history.go(-1);</script>';
            exit;
?>