Scott Reilly

This plugin adds a checkbox to the profile page for users which allows them to opt into receiving a notification email whenever a comment is made to the site.
If a comment goes into moderation, only users who have the ability to manage comments on the site will receive the moderation notification email.
By default, all users of the site have the ability to subscribe to notifications about comments. A filter is provided to facilitate use of code to customize the feature’s availability to users.
Note: a “user” is a person with an actual login account for the site. The plugin does not facilitate permitting visitors who do not have an account on the site to be able to subscribe to all comments.
Links: <a href="http://coffee2code.com/wp-plugins/optin-comment-notifications/" rel="nofollow ugc">Plugin Homepage</a> | <a href="https://wordpress.org/plugins/optin-comment-notifications/" rel="ugc">Plugin Directory Page</a> | <a href="https://github.com/coffee2code/optin-comment-notifications/" rel="nofollow ugc">GitHub</a> | <a href="http://coffee2code.com" rel="nofollow ugc">Author Homepage</a>

Optin Comment Notifications

Checkboxes on user profiles to receive emails about new comments. Like it says.

Exactly what you want

Allows users to opt into receiving a notification email whenever a comment is made to the site.

tierrainnovation

*** Please Note: If you have installed v.1, please deactivate, install, and then reactivate the plugin. ***
AJAX Report Comments is a simple yet powerful add-on for any WordPress blog, particularly larger blogs with a higher volume of user comments. It provides blog visitors the ability to report an inappropriate comment to the blog’s moderator with a single click using AJAX and email.
Through the WordPress Admin you can modify many aspects of the plugin including the text of the “Report Comment” link, the resulting “Thank you” message, the email address to send the inappropriate comment to and the layout and content of the generated email itself. You can even modify the HTML surrounding the “Report Comment” link to suit your needs.
After a comment is reported, the email address you specify will receive a message including the text of the reported comment and a link to view the comment on the site. The next version of this plugin will include more admin options and variety of moderation options, such as placing the comment in a moderation queue if more than X number of visitors flag it as inappropriate.

AJAX Report Comments

AJAX Report Comments is a simple yet powerful add-on for any Wordpress blog, particularly larger blogs with a higher volume of user comments.

Optin Comment Notifications vs AJAX Report Comments