  We study the nonequilibrium spin transport through a quantum dot containing
two spin levels coupled to the magnetic electrodes. A formula for the
spin-dependent current is obtained and is applied to discuss the linear
conductance and magnetoresistance in the interacting regime, where the
so-called Kondo effect arises. We show that the Kondo resonance and the
correlation-induced spin splitting of the dot levels may be systematically
controlled by internal magnetization in the electrodes. As a result, when the
electrodes are in parallel magnetic configuration, the linear conductance is
characterized by two spin-resolved peaks. Furthermore, the presence of the
spin-flip process in the dot splits the Kondo resonance into three peaks.
