File cannot be opened becoause it's an unsupported file type or has been damaged

PHP
1

hi can any one help out for single attachment i.e getting error while viewing the attachment i outlook " file cannot be opened becoause it’s an unsupported file type or has been damaged".

Code

$headers .= “Reply-To: “.$from_name.” <”.$from_address.“>
“;
$headers .= “MIME-Version: 1.0
“;
$headers .= “Content-Type: multipart/mixed;boundary=\””.$mime_boundary.”\””.“\r”;

        # File for Attachment
        $my_path = $_SERVER['DOCUMENT_ROOT']."/InstructionsPDF/";
        $file= $_SERVER['DOCUMENT_ROOT']."/InstructionsPDF/".$AttachmentName;    // use relative path OR ELSE big headaches. $letter is my file for attaching.

        # Attachment
        $message .= "--".$mime_boundary."\\r\

“;
$message .= “Content-Type: application/pdf; name=\””.$AttachmentName.“\”“.”\r"; // sometimes i have to send MS Word, use ‘msword’ instead of ‘pdf’
$message .= “Content-Transfer-Encoding: base64”.“\r”;
$message .= “Content-Length: “.filesize($file).”\r”;
$message .= “Content-Disposition: attachment”.“\r”.“\r”;

        //$content = file_get_contents($file);
        $handle=fopen($file, 'r');
        $f_contents=fread($handle,filesize($file));
        $message.= chunk_split(base64_encode($f_contents),"50");
        $message .= "\\r\

\r
“;
$message .= “–”.$mime_boundary.”–\r
\r
";