  In this work we discuss the combined effects of finite-range
electron-electron interaction and finite-range tunneling on the transport
properties of ultrasmall tunnel junctions. We show that the Coulomb blockade
phenomenon is deeply influenced by the interplay between the geometry and the
screening properties of the contacts. In particular if the interaction range is
smaller than the size of the tunneling region a "weakly correlated" regime
emerges in which the Coulomb blockade gap $\D$ is significantly reduced. In
this regime $\D$ is not simply given by the conventional charging energy of the
junction, since it is strongly renormalized by the energy that electrons need
to tunnel over the extended contact.
