[Exim] Routers and Filters

Just making sure I understand this:

* The only way to use a non-system filter is the forwardfile director.

* There is no way to get from a director to a router without rewriting the
envelope. That is, a director can't do what the domainlist router does.

Hmmm.

It might be possible to setup a director for every possibly transport that
would be reached via a router. Sounds like rather a lot of work.

Background:

ISP type setup. Customers can get mail via pop3, UUCP, etc. Some customer
domains are routed over other customer domains; some customer domains are
routed via external domains (both in the style of a MX, that is, the next
host gets to see the original envelope.)

So far, nothing out of the ordinary.

However, all customers should be allowed to use exim filter files (mainly
for spam filtering).

I don't see a good way to do this.

MfG Kai