Email notification of comments made on a MODx blog?

After setting up a MODx blog using Quip, TagLister and the like (see http://rtfm.modx.com/display/revolution20/Creating+a+Blog+in+MODx+Revolution), but I’ve noticed that there is no way to notify previous posters of new comments. Thinking about this, I realize it’s a pain and susceptible to abuse (e.g. if your comments got filled with bot-spam, then all the previous posters would get a bunch of emails that new comments had been posted). That said, it’s still a useful feature. Has anyone implemented this for MODx?

Actually, there’s stuff in the Lexicon about subscriptions, e.g. "quip.unsubscribe_me" ... what’s up with that? How is that set up? Seems like perhaps the comment options might have something to do with that, but I can’t seem to find anything in the docs that pertains to subscriptions.

And there’s an entire table in the database for modx_quip_comment_notify, so this IS supposed to be possible, no?