  We argue that the classical form of the dipole-dipole interaction energy
cannot be used to model the interaction of the bosons in a dilute Bose-Einstein
condensate made of polar atoms. This fact is due to convergence of integrals,
if no additional restrictions are introduced. The problem can be regularized,
in particular, by introducing a hard sphere model. As an example we propose a
regularization consistent with the long range behavior of the effective
potential and with the scattering amplitude of the fast particles.
