[Exim] Where do you specify the system filter?

Excuse me if this is a stupid question but I can't for the life of me find where you specify a system wide filter. Could someone tell me and perhaps point out in which document this is explained.

Thanks in advance Scott

Cualquier opinión expresada en esta transmisión es las del autor. Ella en fecha la derecha no refleja la política, las vistas y las opiniones Napier Computer Systems LTD