Dante Campbell

The DMN (Hush) plugin provides an easy way to disable comments on all post types in WordPress, including posts, pages, and custom post types. This is useful if you do not want to allow comments on your site, or if you want to disable comments for a specific period of time.
The plugin also removes all options related to comments from the WordPress dashboard, including the ability to enable comments on individual posts or pages. This helps to simplify the dashboard and prevent any confusion for users who may not be familiar with WordPress.
The DMN (Hush) plugin can be easily activated and deactivated from the WordPress dashboard, and requires no additional configuration or setup.

DMN (Hush)

The DMN (Hush) plugin allows you to disable comments on your WordPress site.

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.

DMN (Hush) vs CommentMailer