Is there a plugin to notify commenters of one post to receive emails about new comments made on that post? Only commenters who entered emails will be notified.
check this plugin out: http://wordpress.org/extend/plugins/subscribe-to-comments/
you can use a plugin called "comment reply notification" http://wordpress.org/extend/plugins/comment-reply-notification/
ps I didnt know anyone could add comments without leaving their email adress anyway as they could all be spammers then surely?