[Exim] Exim bounces

    When a message this a deny by an rbl I would like a nice message to
be displayed. I did this via the message = " my really long nice message to
the user"... I have two issues though.
1. I would like not to send a bounce if possible but ranter exim spawn an
email somehow including my message as the body.. .
2. If the user doesn't exist it still gives something like this, can this be
excluded?
550 5.1.1 <test@???>... User unknown
<<< 503 valid RCPT command must precede DATA

> DESCRIPTION
>        This  manual  page  describes  the  format of the /etc/hosts
>        file. This file is a simple text file that associates IP
>        addresses with hostnames, one line per IP address. For each
>        host a single line should be present with  the  following
>        information:

>               IP_address canonical_hostname aliases