The influence of dielectric saturation effects and the granularity of a medium on the effective ion-ion interaction and the reorganization energy for electron-transfer processes have been studied using a medium built from dipoles and polarizabilities that are placed on a lattice. It was found that these effects lead to an increased repulsion between equally charged ions and an increased attraction between oppositely charged ions at short distances. It was also found that the estimate of the outer-sphere reorganization energy contribution to the activation energy for electron-transfer processes, made by Marcus and Hush, is at least a factor of 2 too large for small ions with large charges.