I have a main mailing list, and I have a smaller side mailing list for people interested in my path to getting my book published. Someone on the book list subscribed to the main list, but I didn't get a notification. I discovered it by accident when screen sharing to show a friend how to do a basic thing and we saw a "clicked confirmation email" in the middle of his feed. How can I get notified if someone on one list subscribes to the other? Surely there's a way other than clicking through every subscriber on a regular basis........