  We investigated the metal-ordered manganite system YBaMn2O6 using electron
spin resonance (ESR) in the paramagnetic regime across the charge-ordering and
structural phase transition at T_CO = 480 K and T_t = 520 K, respectively. All
ESR parameters exhibit jump-like changes at T_t while the charge-ordering at
T_CO manifests itself only as a weak and broad anomaly. Above T_t the ESR spin
susceptibility is reduced with respect to the dc-susceptibility, indicating
that only the t_2g-core spins of Mn ions contribute to the resonance
absorption. The contribution of the e_g-spins is suppressed by the time scale
of the polaronic hopping process of the e_g-electrons. The linewidth in this
regime is reminiscent of a Korringa-type relaxation behavior. In this picture
the ESR properties below T_t are dominated by the slowing down of the polaronic
hopping process. The charge fluctuations persist down to the temperature T* ~
410 K, below which the system can be described as a charge-ordered assembly of
Mn$^{3+}$ and Mn$^{4+}$ spins.
