Ekstra attachment ved mime mails

Jeg har hurtigt kodet følgende for at kunne sende en mail med én vedhæftning - når mailen ankommer (både Outlook og Thunderbird) er der en ekstra attachment indeholdende indholdet af mailen

Udskifter jeg linien
$send = mail($_POST['toEmail'],$_POST['subject'],stripslashes($_POST['emailContent']),$message);
med
$send = mail($_POST['toEmail'],$_POST['subject'],'',$message);

Er den vedhæftede fil der stadig, dog uden indhold. Hvordan undgår jeg denne ekstra vedhæftede fil ?

Min kode
<?php
    $mimeBoundary = md5(uniqid(mt_rand(), true));;

#    $message = "To: ".$_POST['toEmail']."\r\n";
    $message = "From: ".$_POST['fromName']. " <".$_POST['fromEmail'].">\r\n";
    $message .= "Bcc: ".$_POST['bccEmail']."\r\n";
    $message .= "Reply-to: ".$_POST['replyEmail']."\r\n";
    $message .= "MIME-Version: 1.0\r\n";
    $message .= "Content-type: multipart/mixed; boundary=\"".$mimeBoundary."\"\r\n";
    $message .= "This is a multi-part message in MIME format.\r\n\r\n";
    $message .= "--".$mimeBoundary."\r\n";
    $message .= "Content-type: text/plain; charset=\"iso-8859-1\"\r\n";
    $message .= "Content-Transfer-Encoding:7bit\r\n\r\n";
    $message .= stripslashes($_POST['emailContent'])."\r\n\r\n";

    if (is_uploaded_file($_FILES['pdf']['tmp_name'])) {
        $fileContent = file_get_contents($_FILES['pdf']['tmp_name']);
        $fileContent = base64_encode($fileContent);
        $fileContent = chunk_split($fileContent);

        $message .= "--".$mimeBoundary."\r\n";
        $message .= "Content-type: ".$_FILES['pdf']['type']."; name=\"".$_FILES['pdf']['name']."\"\r\n";
        $message .= "Content-Transfer-Encoding:base64\r\n";
        $message .= "Content-Disposition: attachment; filename=\"".$_FILES['pdf']['name']."\"\r\n\r\n";
        $message .= $fileContent."\r\n\r\n";
    }
    $message .= "--".$mimeBoundary."\r\n";

    $send = mail($_POST['toEmail'],$_POST['subject'],stripslashes($_POST['emailContent']),$message);
    echo "sendt !";
?>