  In this work, a constant and uniform magnetic field is less than the
Schwinger critical value. In turn, an additional constant and uniform electric
field is taken much smaller than the magnetic field value. The propagation of a
photon in this electromagnetic field is investigating. In particular, in the
presence of a weak electric field, the root divergence is absent in the photon
effective mass near the thresholds of pair creation. The effective mass of a
real photon with a preset polarization is considered in the quantum energy
region as well as in the quasiclassical one.
