What e+e- collider could make a ''no-lose'' search for minimum supersymmetric standard model Higgs bosons?

The lightest CP-even Higgs boson h in the minimal supersymmetric standard model (MSSM) has a mass upper bound depending on the top quark and squark masses. An e+e- collider with enough energy and luminosity to produce h+Z at measurable rates up to the maximum h mass would cover the entire MSSM parameter space if h+A production was also searched for. We explore the energy and/or luminosity needed for various top quark and squark masses. For mt=150 GeV and a 1 TeV supersymmetric mass scale, a 230 GeV collider with 10 fb-1 luminosity would suffice, based on e+e-→hZ,hA→ττjj signals. With future b tagging, other channels will contribute important additional signals and the luminosity requirements will be lowered by up to an order of magnitude