Therefore there is a chance of me receiving a take-down request that I am happy to action, but I would be unable to 'take-down' all the emails that have already been sent out. Is there a practical solution you can think of?
Yes. Speak to a lawyer.
PPRuNe is not the place for legal advice.
If you are knowingly transmitting information that you are aware is likely to be subject to 'take-down' requests, then legal advice is very much what you need if you're hoping to find a way to do it that will land you in the least amount of hot water possible.