It may no longer be a binary choice, but if your input is 'woman' and the tool indicates a 90%+ chance of the result being male, then your tool is crap.
"we were not sure if it is worth our time and efforts to make a change in existing biased reality "
It seems obvious that the time and effort to correct this monumental cock-up is going to be well beyond your ability. It also seems to me that equating gender with email is beyond stupid.
At least you were intelligent enough to abandon the project.