That's interesting that you thought it was older, it's worth taking notes of this.
I agree that the open-source part is the USP for ForwardEmail that we haven't. The thing on our end is that we have already thought about opensourcing a few parts of our service, but if we don't do all, it doesn't matter to do partially.
So instead, we plan to have an audit from an external service to guarantee that what we say and offer is aligned with the respect of our users and privacy. That's the next step :)