An interference canceller is described, wherein the interference canceller includes an input receiving an input composite signal, a reference circuit, and a cancellation circuit. This is provided by a tilted card cage with a backplane mount for the scanhead connectors which extends above the top of the card cage. Transmission of the email is thus deferred until the email has been reviewed. The silicone oil phase contains less than about 5% by weight of the emulsion of a non-volatile oil and includes about 2% to about 25% by weight of the emulsion of a volatile linear silicone.