  We study infrared divergences due to ultraviolet-infrared mixing in quantum
field theory on Moyal space with Lorentzian signature in the Yang-Feldman
formalism. Concretely, we are considering the phi^4 and the phi^3 model in
arbitrary even dimension. It turns out that the situation is worse than in the
Euclidean setting, in the sense that we find infrared divergences in graphs
that are finite there. We briefly discuss the problems one faces when trying to
adapt the nonlocal counterterms that render the Euclidean model renormalizable.
