带有附件的电子邮件在gmail上工作但在Outlook或我的邮件服务器上没有

I already checked the similar questions on site but didn't find anything. I am sending an attachment with the email which generates on the form submission. It is working great on Gmail but on Outlook or on my office mailserver, the email is coming with empty attachment. To be precise the attachment is coming without any data in it.

Here is my code:

$row = $this->model_catalog_bulk_order_reset->getresetinfotest($orderid)->rows;
$filename= $orderid;
$filename='excel/'.$filename.'.csv';
$fp=fopen($filename,"w");
$seperator="";

foreach($row as $name =>$value)

{
    if($name==0){

        $seperator="";

        $comma="";
        foreach($value as $name =>$value)

        {

        $seperator.=$comma.''.str_replace('','""',$name);
        $comma=",";

        }

        $seperator.="
";
        fputs($fp,$seperator);
    }


}

foreach($row as $name =>$value)

{
    $seperator="";

    $comma="";
    foreach($value as $name =>$value)
    {
        $newValue = explode('-',$value);

        $count = count($newValue);

        if($count > 1){

            $value = $newValue[0]." to ".$newValue[1];
        }else{
            $value = $newValue[0];
        }


        $seperator.=$comma.''.str_replace('','""',$value);
        $comma=",";

    }

    $seperator.="
";
    fputs($fp,"'".$seperator);

}

fclose($fp);
$filename= $orderid;
$my_file = $filename.'.csv';
$filename = $filename.'.csv';
$path = "excel/";


$from_name = "XYZ";

$from_mail = $this->config->get('config_email');

$mailto = $customer_record['email'].",".$this->config->get('config_email');

$subject = "Bulk order.";

$body = "Hi,
 Please find the attachment?";

$replyto=$this->config->get('config_email');
$file = $path.$my_file;
    $file_size = filesize($file);


$handle = fopen($file, "r");

$content = fread($handle, $file_size);

fclose($handle);

$content = chunk_split(base64_encode($content));

$uid = md5(uniqid(time()));

$name = basename($file);

$eol = PHP_EOL;

 $header = "From: ".$from_name." <".$from_mail.">".$eol;

$header .= "Reply-To: ".$replyto.$eol;

$header .= "MIME-Version: 1.0
";

$header .= "Content-Type: multipart/mixed; boundary=\"".$uid."\"";


$message = "--".$uid.$eol;

$message .= "Content-type:text/plain; charset=iso-8859-1".$eol;

$message .= "Content-Transfer-Encoding: 7bit".$eol.$eol;

$message .= $body.$eol;
$message .= "--".$uid.$eol;

$message .= "Content-Type: application/octet-stream; name=\"".$filename."\"".$eol; 

$message .= "Content-Transfer-Encoding: base64".$eol;

$message .= "Content-Disposition: attachment; filename=\"".$filename."\"".$eol;

$message .= $content.$eol;

$message .= "--".$uid."--";

mail($mailto, $subject, $message, $header);

Any help is appreciated. Thanks

Well phpMailer fixed it.

    $subject = "Bulk Order";
    $message = "Hello!";

    $mail = new Mail();
    $mail->protocol = $this->config->get('config_mail_protocol');
    $mail->parameter = $this->config->get('config_mail_parameter');
    $mail->smtp_hostname = $this->config->get('config_mail_smtp_hostname');
    $mail->smtp_username = $this->config->get('config_mail_smtp_username');
    $mail->smtp_password = html_entity_decode($this->config->get('config_mail_smtp_password'), ENT_QUOTES, 'UTF-8');
    $mail->smtp_port = $this->config->get('config_mail_smtp_port');
    $mail->smtp_timeout = $this->config->get('config_mail_smtp_timeout');

    $mail->setTo($customer_record['email']);
    $mail->setFrom($this->config->get('config_email'));
    $mail->setSender(html_entity_decode($this->config->get('config_name'), ENT_QUOTES, 'UTF-8'));
    $mail->setSubject($subject);
    $mail->setText($message);
    $mail->addAttachment($filename);
    $mail->send();