Send multiple attachments via Email

I have a form where text fields must have an option to upload multiple files at once and then send them all via Email. My code is working when attaching only one file, I get everything right. When I attach several, I also receive the email, but only one file is attached. Can someone help me? To attach all selected files to Email.

Index:

<form action="MulAttachMail.php" method="post" enctype="multipart/form-data">
                    <h3>De: </h3>
                    <label>Seu Nome (opcional): </label> <input type="text" name="" class="" placeholder="Digite seu Nome"/>
                    <label>Seu Email: </label> <input type="email" name="sen_email" class="sen_email" placeholder="Digite seu Email"/>
                    <h3>Para: </h3>
                    <label>Email do Destinatário: </label> <input type="email" name="rec_email" class="rec_email" placeholder="Email da pessoa que vai receber o contato"/>
                    <label>Assunto: </label>
                    <input type="text" name="email_sub" class="" placeholder="Assunto da mensagem"/>
                    <label>Mensagem: </label> 
                    <textarea name="box_msg" rows="10" cols="30"></textarea>
                    <div class="input_fields_wrap">
                        <div><input type="file" name="attachment" value="Attach File" id="first_attach" multiple></div>
                    </div>
                    <a class="add_field_button">Adicionar Mais Arquivos</a>
                    <input type="submit" value="Enviar" id="submit"/>
                </form>

MulAttachMail.php - which sends and receives information -

<?php
// Include PHPMailerAutoload.php library file
include ("lib/PHPMailerAutoload.php");

$sen_name = "";
$sen_email = "";
$rec_email = "";
$email_sub = "";
$box_msg = "";
// Retrieving & storing user's submitted information
if (isset($_POST['sen_name'])) {
    $sen_name = $_POST['sen_name'];
}
if (isset($_POST['sen_email'])) {
    $sen_email = $_POST['sen_email'];
}
if (isset($_POST['rec_email'])) {
    $rec_email = $_POST['rec_email'];
}
if (isset($_POST['email_sub'])) {
    $email_sub = $_POST['email_sub'];
}
if (isset($_POST['box_msg'])) {
    $box_msg = $_POST['box_msg'];
}

if (isset($_FILES) && (bool) $_FILES) {
    $files = array();
    $ext_error = "";
    // Define allowed extensions
    $allowedExtentsoins = array('pdf', 'doc', 'docx', 'gif', 'jpeg', 'jpg', 'png', 'rtf', 'txt','zip');
    foreach ($_FILES as $name => $file) {
        if (!$file['name'] == "") {
            $file_name = $file['name'];
            $temp_name = $file['tmp_name'];
            $path_part = pathinfo($file_name);
            $ext = $path_part['extension'];

            // Checking for extension of attached files
            if (!in_array($ext, $allowedExtentsoins)) {
                echo "<script>alert('Sorry!!! ." . $ext ."Extension is not allowed!!! Try Again.')</script>";
                $ext_error = FALSE;
                }else{
                $ext_error = True;
            }

            // Store attached files in uploads folder
            $server_file = dirname(__FILE__) . "/uploads/" . $path_part['basename'];
            move_uploaded_file($temp_name, $server_file);
            array_push($files, $server_file);
        }
    }
if($ext_error != FALSE){
    $mail = new PHPMailer();
    $mail->IsSMTP();
    $mail->SMTPSecure = "tsl"; //tls
    $mail->CharSet = 'utf-8';
    $mail->Host = "mail.hostname.com";
    $mail->Port = 587;
    $mail->SMTPAuth = true;
    $mail->Username = "[email protected]"; 
    $mail->Password = "senhadoemail"; 

    // Sender Email address
    $mail->From = $sen_email;

    // Sender name
    $mail->FromName = $sen_name;

    // Receiver Email address
    $mail->addAddress($rec_email);

    // Attaching files in the mail
    foreach ($files as $file) {
        $mail->addAttachment($file);
    }
    $mail->Subject = $email_sub;
    $mail->Body = $box_msg;
    $mail->WordWrap = 50;

    // Sending message and checking status
    if (!$mail->send()) {
        echo "<script>alert('Sorry!!! Message was not sent. Mailer error:  " . $mail->ErrorInfo . ")</script>";
        exit;
    } else {
        echo "<script>alert('Congratulations!!! Your Email has been sent successfully!!!')</script>";
    }
    // Deleting files from the uploads folder
    foreach ($files as $file) {
        unlink($file);
    }
    echo "<script>window.location='index.php';</script>";
}else{
    foreach ($files as $file) {
        unlink($file);
    }
    echo "<script>window.location='index.php';</script>";
}
}
?>