[Exim] Fetching userfilters from db instead of file.

I have got a virtual setup, where (almost) all userinformation is kept
in a suitable db.

This works very well with just about everything I want to do. Now, I want
to go all the way, and even fetch the filters out of the db (these are in
turn generated from a web interface).

What is the best way of doing this?

I seem to have the following choices:

1) Everything to a fixed file, which starts a perlscript which does the db
lookup.
2) Embedded perl (ouch...)
3) A systemwide filter which I regenerate every time somebody changes
something.

What I really want is a way of telling a director to do a ${lookup in a
db, and use the result as a filter. How could one do this?

Any way of using filters without having to use files? Any ideas?

(I think I saw somebody ask about this earlier, but I can't seem to find
that message again)
--
Thorkild