We determine the liquid-vapor coexistence curve of the restricted primitive model of electrolytes by means of Monte Carlo simulations in the Gibbs ensemble. Our results confirm earlier findings of Panagiotopoulos [Fluid Phase Equilibria 76, 97 (1992)]. A study of the electrical properties of the two coexisting phases reveals that the second Stillinger-Lovett condition is verified in the liquid but not in the vapor. This means that the latter could be dielectric.