This plugin is exactly what I've been looking for all this time for WordPress. It's how sites like deviantArt and LiveJournal handle the comment reply function, which is: when a comment is posted, the author can reply to that particular comment, and that comment author gets some sort of notification -for their reply only-. The comment author won't get bombarded with all the other replies to the post, and won't have to subscribe to anything. This just makes sense to me, especially when by default a commenter is required to type in their email anyway.
The only iffy about this plugin is that the plugin author is not very fluent in English, so the documentation is a bit sparse. Most options are self-explanatory anyway.
The options I activated are:
[x] Replied by the author of the post or administrator ONLY
[x] Reply in WordPress Admin Panel
[x] Enabled In-the-post comment management
The only option that I had to play around a bit to figure out how it works is the Enabled In-the-post comment management and how to move threads around. This was what I found:
* Once enabled, a textbox with a number appears next to each comment
* To move comment-A under comment-B, type comment-B's number into the textbox next to comment-A
* To then move comment-A out of a thread, type '0' into comment-A's textbox
For Edit the subject of notification email, I used:
blogname Reply to '[postname]'
For Edit Notification Message, I simplified it to:
<p><strong>Reply from <a href="[blogurl]">MyName</a>:</strong><br /> [cc_content]</p> <hr /> <p><strong>Your original comment at:</strong><br /> <a href="[commentlink]">[commentlink]</a><br /> [pc_content]</p> <hr /> <p>Please do not reply to this address! To contact MyName directly, reply to <a href="mailto:MyEmail@MyEmail.com">MyEmail@MyEmail.com</a></strong>. Thanks for your comment!</p>
I hope this helps. I'm really in love with this plugin :D