PHP send email with attachment

mail_att.php

<?php
/*====================================*/
/*===  Send email with attachment ====*/
/*====================================*/
function mail_attachment($to, $subject, $message, $from, $file, $reply_to) {
  // $file should include path and filename
  $filename = basename($file);
  $file_size = filesize($file);
  $content = chunk_split(base64_encode(file_get_contents($file))); 
  $uid = md5(uniqid(time()));
  $from = str_replace(array("\r", "\n"), '', $from); // to prevent email injection
  $header = "From: ".$from."\r\n"
	  ."Reply-To: ".$reply_to."\r\n"
	  ."MIME-Version: 1.0\r\n"
	  ."Content-Type: multipart/mixed; boundary=\"".$uid."\"\r\n\r\n"
	  ."This is a multi-part message in MIME format.\r\n" 
	  ."--".$uid."\r\n"
	  ."Content-type:text/html; charset=iso-8859-1\r\n"
	  ."Content-Transfer-Encoding: 7bit\r\n\r\n"
	  .$message."\r\n\r\n"
	  ."--".$uid."\r\n"
	  ."Content-Type: application/octet-stream; name=\"".$filename."\"\r\n"
	  ."Content-Transfer-Encoding: base64\r\n"
	  ."Content-Disposition: attachment; filename=\"".$filename."\"\r\n\r\n"
	  .$content."\r\n\r\n"
	  ."--".$uid."--"; 
  return mail($to, $subject, $message, $header);
 }
?>