yakuphan

Comment Approved Notifier sends an e-mail to your commenters when you approve their comments. It is a very simple plugin. There are no settings, options. It starts to work when you activate it.
<h4>Read Please</h4>
If you upgraded to WP 2.7 or WP 2.8, please, update v1.1 to v2.1 
It requires at least 2.7. If you use WP 2.6.5, please use version 1.1
Thanks!

Comment Approved Notifier

https://wordpress.org/plugins/comment-approved-notifier-extended/
Updated version of this plugin. forked.

Updated

The plugin sends an e-mail to your commenters when you approve their comments.

ramon fincken

A plugin that automatically schedules pending comments for approval, depending on a min/max threshold and the last comment’s publish date and time. 
 When a comment is posted or when the admin is logged in, the plugin computes the most recent interval when a comment can be auto approved and picks a timestamp in that interval when to approve the pending comment. 
 Optional: Notify the site admin by email when a comment is approved. 
 Warning All pending comments will be scheduled, make sure you have an antispam plugin in place. <a href="https://wordpress.org/extend/plugins/antispam-for-all-fields/" rel="ugc">I wrote one over here</a>. 
 Based on: <a href="https://wordpress.org/extend/plugins/automatic-post-scheduler/" rel="ugc">Automatic Post Scheduler</a> by <a href="https://profiles.wordpress.org/users/tetele/" rel="nofollow ugc">Tetele</a>
Coding by: <a href="http://www.mijnpress.nl" rel="nofollow ugc">MijnPress.nl</a> <a href="http://twitter.com/#!/ramonfincken" rel="nofollow ugc">Twitter profile</a> <a href="https://wordpress.org/extend/plugins/profile/ramon-fincken" rel="ugc">More plugins</a>

Automatic Comment Scheduler

A plugin that automatically schedules pending comments for approval, depending on a min/max threshold and the last comment's publish date and tim …

Comment Approved Notifier vs Automatic Comment Scheduler