In the past my users have asked for me to install comment subscription plugins. I used Subscribe2. However, Subscribe2 relies on the wp_user table to store subscriber details.
I do not allow new user accounts on my blogs for simplicity; S2 opened up an obvious hole by allowing every spammer and its dog to register user accounts without my permission.
However, my users are still keen to have this function. Can anyone point me to a plugin that provides comment subscriptions without adding new users to the wp_users table?