[Exim] external script launch?

Is it possible to launch an external script from the ACL? Specifically, when the end
of the acl is reached, instead of just returning the "No relaying allowed" error I also
want to launch a script that slaps down a temporary ip block via iptables. For
performance purposes, I don't want exim to wait for the script to terminate, just fork
it and continue with its own business (shoot and scoot).

I already have a similar system implemented for my web server to deal with some
common exploits like CodeRed and Nimda.

Rossz