You mentioned Jetpack earlier so you might already know about going to ‘Jetpack > Site Stats > Subscriptions > Followers, then clicking the ‘blog’ link to get a downloadable list of email followers.
I like to put myself in the user’s shoes and understand their experience, so I often create a test user profile using a different email address. I can then assign it different roles, log in as that user and see what capabilities and notifications apply. Maybe give that a shot.