[Exim] Exim as a black hole

Hi!

I need an advice on how to configure Exim to act as a "black hole".
In more details, it usually does accept and forward all the inbound mails to
a particular host. But, if that host is down or the system (where the Exim is
installed) runs out of disk space, I want Exim just to accept and silently
trash all the mails, prolly by puting them in /dev/null. So the basic idea is
that Exim must reponse to inbound requests at all cost.

Have some idea ? Please share it with me! :)

--
BR/Hristo.