We have carried out ac conductivity measurements on different alkali tellurite and silver halide containing glasses exhibiting high electronic polarizabilities. The analysis of the conductivity spectra provides strong evidence that the ionic site energy distributions in these glasses are distinct from those in conventional glasses with low electronic polarizabilities, such as silicate, borate, and phosphate glasses. Our results can be explained by postulating a vacancy-type transport mechanism, i.e., by assuming that a high electronic polarizabilty of the glassy network leads to a small and temperature-dependent ratio of empty ionic sites to mobile ions.