[Exim] Angry users because we use rbl_domains

Hey Folks!

We provide mail service for our customers.

Does anyone have some new idea how to explain to them why we have
rbl_domains set?
Seems as if they are considering to look for a new provider because they
can't receive mail from THEIR customers because the sending systems appear
in the ORBS database.

I tried everything that came to my mind to explain the functionality and
advantages to them.
I told them that OTHER systems have the problem, not OURS.
The customer considered this to be censorship.

Any ideas? Experience?

Thanks

Daniel