  We study the prospects of thermal leptogenesis in the framework of the
minimal flipped $SU(5)$ unified model in which the RH neutrino mass scale
emerges as a two-loop effect. Despite its strong suppression with respect to
the unification scale which tends to disfavor leptogenesis in the standard
Davidson-Ibarra regime (and a notoriously large washout of the $N_1$-generated
asymmetry owing to a top-like Yukawa entry in the Dirac neutrino mass matrix)
the desired $\eta_B\sim 6\times 10^{-10}$ can still be attained in several
parts of the parameter space exhibiting interesting baryon and lepton number
violation phenomenology. Remarkably enough, in all these regions the mass of
the lightest LH neutrino is so low that it yields $m_\beta \lesssim 0.03$ eV
for the effective neutrino mass measured in beta-decay, i.e., an order of
magnitude below the design sensitivity limit of the KATRIN experiment. This
makes the model potentially testable in the near future.
