[exim] unrouteable address

Hi

We have a mailing server which runs exim4 we have the mail gateway which
recieves the mails for our domain and delivers them to the mail server above
mentioned. The real users exist in the mailing server above and not in the
gateway server. As such all junk user @our domain mails also are received
and queued as mailer-daemon unrouteable address mails in the above server.
WE have split configuration with acl section having the check_rcpt config
file. Also main config has acl_smtp_rcpt=acl_check_rcpt. How to just delete
the junk user mails and not queue them up building the mailq

thanks for any help
==========================================================
acl_check_rcpt:
  accept hosts = :
  deny    domains       = +local_domains
          local_parts   = ^[.] : ^.*[@%!/|]
          message       = restricted characters in address
  deny    domains       = !+local_domains
          local_parts   = ^[./|] : ^.*[@%!] : ^.*/\\.\\./
          message       = restricted characters in address
 accept local_parts = *
             domains = +local_domains
   deny message = Sender verification failed
        !acl = acl_whitelist_local_deny
        !verify = sender
   warn message = X-Broken-Reverse-DNS: no host name found for IP address 
$sender_host_address
   !verify = reverse_host_lookup
  deny message = sender envelope address $sender_address is locally 
blacklisted here. If you think this is wrong, get in touch with postmaster
       !acl = acl_whitelist_local_deny
       senders = ${if exists{CONFDIR/local_sender_blacklist}\
                             {CONFDIR/local_sender_blacklist}\
                             {}}

  deny message = sender IP address $sender_host_address is locally   
   blacklisted here. If you think this is wrong, get in touch with postmaster
       !acl = acl_whitelist_local_deny
       hosts = ${if exists{CONFDIR/local_host_blacklist}\
                             {CONFDIR/local_host_blacklist}\
                             {}}
  accept domains = +local_domains
         endpass
         message = unknown user
         verify = recipient
  accept domains = +relay_to_domains
         endpass
         message = unrouteable address
         verify = recipient
  accept hosts = +relay_from_hosts
         verify = recipient
  accept authenticated = *
  deny message = relay not permitted
==============================================

Thanks & Regards

Kausalya Ramaswamy
Scientific Officer - C
Computer Centre, TIFR,
Mumbai - 400005. INDIA