While you can’t always control who introduces you via email, you can control how you introduce others and your role from that point on.
Ask both parties individually if they would like to be connected. Briefly explain why it might be a fit. Once approved, email a short introduction to both, closing with, “Happy connecting. No need to copy me further.”
When I’m the email intro recipient, I reply and include the original sender, thanking them for making the connection. After that I don’t copy them on the future emails between me and my new contact – just as they requested.