[exim] listed at Backscatterer.org

Hi list,

my mail server has been listed at backscatterer.org, and on their site
they suggested that i should only send bounces to local users but i dont
know how to implement this in exim. recently i found out that some of
the ip's i allow relay for are infect and send a lot of mails with fake
sender addresses, is their a way in exim that i can allow only senders
with local + "accepted" domains to relay mails from my mail server. eg:
that i allow a user@??? from <1.2.3.4> to relay through my
server but user@??? from <1.2.3.4> not relay or send any
mails. this will really help me as now what i normally do is block the
smtp for the specific ip sending those spams which affect any legitimate
emails. I really need help on this two problems. here is an example from
the backscattere website.

Backscatterer - Why it is abusive and how to stop your system doing so

Email servers should be configured to provide Non-Delivery Reports
(bounces) to local users only.
Unacceptable email from anywhere else should be rejected.

Thanks
Kebba