Mail_Mime reply to not working with error messages

Hi all. I've created a little command line PHP script to send mail. But with error messages (user unknow, domain unknown, etc), it sends back to the user who executed the script not the Reply-To I specify in my script. Using Mail_Mime I've setup my headers like so: $hdrs = array(

   'From'    => $from,

'Subject' => $subject, 'Return-Path' => $from, 'Reply-To'=> $from ); But the mail always gets returned to whatever user executed the script. For example I have $from = dsi-randomnumber@domain.com; and from the commandline I execute it as user keith, and that's where the message gets boucned back to when there is a error. Can anybody tell me what I need to set so errors messages get returned to user I specify in my PHP script rather than who sends it. Thanks, Keith