Send to member’s registered email

Hi,
I really like the idea of letting users subscribe to updates/comments for a post without needing to leave a comment. Is there a way to make it just use their registered email address? I would actually like to require members to register for this functionality. I worry that anybody can just enter any email address for any post and I would like them to just register once, confirm their email and then choose what posts they would like to receive updates for. This seems to have a very high potential and thank you!