[exim] Restricting sending/receipt

Hi all -

I need a little advice on how to approach something. I'm running exim
for use in a virtual domain environment. I force everybody to
authenticate over TLS before relaying.

One of the domain owners wants to restrict certain particular users
within his domain from sending or receiving email outside that domain.
So, for instance, while "mark@???" might be able to receive and
send wherever, "jeff@???" is only able to receive/send from/to
the "domain.name" domain.

What's the best way to approach this? I'm imagining that I'll need to
take separate approaches for receiving and sending. Is this best done
with routing rules? Or just use ACLs? Can anybody offer a rough
approach with either method?

Thanks in advance.

--
"The memory management on the power pc chip is something that should be
shown to small children when they've been especially bad." -Linus Torvalds

Cole Tuininga
Lead Developer
Code Energy, Inc
colet@???
PGP Key ID: 0x43E5755D