  We find the propagator and calculate the tree level scattering amplitude
between two covariantly conserved sources in an Anti-de Sitter background for
the most general D-dimensional quadratic, four-derivative, gravity with a
Pauli-Fierz mass. We also calculate the Newtonian potential for various limits
of the theory in flat space. We show how the recently introduced three
dimensional New Massive Gravity is uniquely singled out among higher derivative
models as a (tree level) unitary model and that its Newtonian limit is
equivalent to that of the usual massive gravity in flat space.
