[Exim] (no subject)

Hello,

I need to setup a configuration with exim as follows:

1. Exim requires SMTP authentication, so we have a $authenticated_id for
later use
2. Certain (authenticated) users may send only to local recipients
3. Certain users may send everywhere
4. Certain users may send mail locally *and* to certain non-local recipients
specified in a database/file, on a per-user basis

Nr. 4 means, for example:
User A can send mail to xyz@??? and abc@???
User B can send mail to def@???
and so on

No. 1 to 3 seem no problem, using the "senders" option on a router would
allow me to filter out which users can send to non-local recipients. But how
would I best do No. 4?
I believe I need to set up some "condition" on the appropriate routers, but
what would it look like?
I'd personally prefer dbm lookups, but lsearch or anything the like would be
OK, too.

Thanks,
Andreas