I'm looking for a plugin that will notify registered users of new comments made to any post that they are interested in.
To give a scenario to explain:
Let's say that Joe as one of the contributors to a blog makes a post.
Then Tim, a registered user, likes Joe's post, and wants to see what further comments are made in response. I would like for a plugin to be installed that allows Tim to check a checkbox.
Then once he does this, when Mary comes along and makes a comment on Joe's post, Tim will receive an email at the address that he signed up with.
I would like that Joe (and any other registered user) could also tick the checkbox so that they also get emails notifying them of comments made to the post. The notifications don't have to contain the comments.
Can anyone point me to a plugin or core WP functionality that will do this? I have seen the 'Settings' > 'Discussion' options, but they will only allow the Admin to receive notifications. I also checked out the Post Notification plugin, but that was confusing, and it wasn't clear whether it would do what I want or not.