In our previous work [10], for a given Riemann surface Y 0 with marked handle, we investigated geometric properties of the set of marked onceholed tori X allowing holomorphic mappings of X into Y 0 . It turned out that it is a closed domain with Lipschitz boundary. In the present paper we show that the boundary is never smooth. Also, we evaluate the critical extremal length for the existence of holomorphic mappings in terms of hyperbolic lengths.