If it is from the saildrive then there is one further consideration. Is the oil “milky”, not simply the oil that leaked but the oil in the saildrive. It would be worth getting a small sample to check; but do this after motoring for a while so the oil is well mixed. People say “milky” but actually the colour of mayonnaise so more cream coloured. If so then the shaft seals (or less likely the seal on the drain plug) may have failed. This can result in water getting into the saildrive and pushing the oil up. If this is the case then it needs fixing before water or lack of oil causes damage in the saildrive itself.