lynch's vanishing theorem for generalized whittaker modules applies to generic homomorphisms of the nilradical of a class of parabolic subalgebras which we have named nice. in this talk we describe the classification of nice parabolic subalgebras of simple lie algebras. our results give rise to a new characterisation of even nilpotents. we will also give a normal form of richardson elements for nice parabolic subalgebras in the classical case.