Mach's principle, gravitation and electromagnetism: The electromagnetic inertia of charged elementary particles

The question of the magnitude and behaviour of the electro-magnetic contribution of the mass of an elementary charged particle is explored. It is shown that, if the ''cut-off'' of the relativistic quantum electrodynamics is taken as an approximation to the physical process embodied in the postulates: 1. That the bare charge of an elementary particle may be only emit and absorb virtual photons having energies that are integral multiples of some fundamental energy, and that 2. the observed charge of an elementary particle is a constant independent of its ''radius'', the electromagnetic mass of such a particle is always finite, even when the radius of the particle becomes zero. Alternative postulates that will resolve the out-off dilemma are briefly discussed