Huda Toriq

CommentMailer is a WordPress plugin that generates and sends e-mail to your blog’s commenters to tell them that you 
have replied his/her comment on your blog’s comment system. It adds extra options on your blog’s comment form to select 
which commenters you are replying to. Submitting the reply comment will trigger the e-mail generation function thus 
send them automatically. You can customize your own notification e-mail or use the default one.

CommentMailer

Send automated email to your blog's commenters everytime you reply their comments on the blog's comment system.

Stefano Lissa

Comment Notifier lets user to subscribe the comment thread of each single post of your blog. It improves traffic and loyalty.
Notification emails are fully customizable (both plain text or html) with a number of “tags” to insert author name, post link and title, receiver name and so on.
The “subscribe me” checkbox in the comment form area can be added automatically or manually.
Read more on <a href="http://www.satollo.net/plugins/comment-notifier" rel="nofollow ugc">Comment Notifier</a> offical page.
<h4>Other plugins</h4>
<ul>
<li><a href="https://www.satollo.net/plugins/hyper-cache" rel="nofollow ugc">Hyper Cache</a></li>
<li><a href="https://www.thenewsletterplugin.com" rel="nofollow ugc">Newsletter</a></li>
<li><a href="https://www.satollo.net/plugins/header-footer" rel="nofollow ugc">Header and Footer</a></li>
<li><a href="https://www.satollo.net/plugins/thumbnails" rel="nofollow ugc">Thumbnails</a></li>
<li><a href="https://www.satollo.net/plugins/include-me" rel="nofollow ugc">Include Me</a></li>
</ul>

Comment Notifier

Add comment subscriptions to the blog comment form.

CommentMailer vs Comment Notifier