treeflips

Yin Zhongzhen

This simple plugin automatically sends a notification email to commenters when someone replies to their comment. This feature can be enabled automatically by the site admin, or through an opt-in/opt-out checkbox below comment section on frontend.
It’s best to use it with an email-sending plugin like WP Mail SMTP, and with SMTP or transactional email service like SendGrid or Mailgun. Sending from your server via PHPmailer can cause deliverability issues (email notfications caught in spam).
I loved the original plugin <a href="https://wordpress.org/plugins/comment-reply-notification/" rel="ugc">Comment Reply Notification</a> (by @denishua) for its simplicity but it was abandoned and stopped working years ago. So I forked and revived it to work with the latest PHP and WordPress. I also improved some wording, removed unnecessary author links in the email notifications, and also keep it more updated. Credits to Denis who first hacked it 5 years ago, and later Walter for fixing string escapes.
<h4>Features:</h4>
<ul>
<li>Feature modes – disabled, author/admin replies only, automatically, checkbox opt-in.</li>
<li>Edit email notification – subject and message.</li>
<li>[year] shortcode for dynamic year in email templates.</li>
<li>Developer-friendly hook for adding custom shortcodes.</li>
<li>Fixes issue with email notifications for moderated comments.</li>
<li>Can delete plugin options – after deactivation.</li>
</ul>

Comment Reply Email

Commenters can receive email notifications of replies to their comments.

Yakup Hoca

The visitors send their questions in comments, then they leaves our web sites. When we reply their comment to answer their questions, this plugin sends an e-mail about this. So that, the visitor will learn this situation and return to our site to read our answer.
For support: <a href="http://www.yakuphoca.com/comment-reply-by-admins-notifier-plugin/" title="Support by Yakup Hoca" rel="nofollow ugc">Plugin URI</a>

Comment Reply by Admins Notifier

This plugin sends an e-mail notify when an admin or an editor of site reply a comment.

Comment Reply Email vs Comment Reply by Admins Notifier