MAILER-DAEMON messages

How can I get these sent to me?

[fish_eye]

I've just created my first mailout program which I am testing.

My problem is I'm not getting any of the bounced emails that I'm expecting.

I have control over my php.ini but I've been told I can also specify <something> in my "envelope". I'm happy to use either technique. (Running Apache Linux etc.)

Can someone please tell me what the <something> I need to set is and where it's best to do it (I guess the ini file)?

PS. I'm currently using imap_mail() to do the send but I have no cc etc so I'm happy to change to something else.

[fish_eye]

Just in case anyone's interested...

$mail_from = "-f<theemailtobouncebackto>";
$result = mail($recipient, $subject, $message, $mail_header, $mail_from );

...did the trick (and perhaps a few config settings).