  We discuss the antiGZK effect in the diffusive propagation of ultra high
energy protons in intergalactic magnetic fields, which consists in a jump-like
increase of the maximum distance from which ultra high energy protons can reach
an observer. The position of this jump, $E_j \approx 2\times 10^{18}$ eV, is
determined exclusively by energy losses (transition from adiabatic to
pair-production energy losses) and it is independent of the diffusion
parameters. The diffuse spectrum presents a low-energy steepening approximately
at this energy, which is very close to the position of the second knee observed
in the cosmic ray spectrum. The dip, seen in the universal spectrum as a
signature of the interaction with the cosmic microwave background radiation, is
also present in the case of diffusive propagation in magnetic fields.
