[exim] relaying

Hi

We are running exim4.42.
Currently we are open for relaying..

Here is our relay rules in the mail sction of the configuration file

domainlist local_domains = wits.ac.za
domainlist relay_to_domains = *.wits.ac.za:dragonzone.za.net:timetwist.za.net:mu
d.za.net:wicca.za.net:wax.za.net:icam.za.org:fotim.ac.za:drastico.za.net:icam.za
.org:gothicparents.za.net:nixxie.za.net:sehnsucht.za.net:dekan.co.za:iaphys.org:
iaphys.com:cosalc.ac.za
hostlist relay_from_hosts = 127.0.0.1 : 146.141.0.0/16

This doesn't seem to stop relaying.

As we fear being blacklisted we need to block relaying completely.

How do we go about doing this.

Any help would be greatly appreciated.

Thanks
sherona