[Exim] Routing individual addresses on a mailhub

Hi,
I try to configure a Mailhub in a star topology which shoud route
user1@example to left.example and user2@example to right.example.
All this shoud work with our central LDAP-server. So i tried something
like this:

ldap_verteiler:
driver = manualroute
domains = +relay_to_domains
transport = remote_smtp
route_data = ${lookup ldap \
{ldap:///mail=${recipients},ou=ma,dc=bfi-burgenland,dc=at?mailHost?base?}}

which (i know) can not work because of "$recipients" is not known.
Another question is, what happen if there are more then one recipients.

How could i get this work?
Thanks
Andreas Grabner


PS: currently i do the same with exim3 and an "alias"-file including
domains., but i would like to do aliasing on the other mail-servers.

PPS: ist da jemand im Raum Oberwart (österreich) mit einem exim4 buch
das er mir borgen könnte bis meines geliefert werden kann (2 Wochen)