The plugin has a really simple purpose. It allows your visitors to recommend your content (any of your posts) to a friend.
WP-EMail includes an additional link below your post’s headline labeled as “Email This Post.”
Such a feature is very helpful to the reader. Email still is the main and the fastest way of exchanging information online. People are used to it much more than to any social media network – regardless of what some social media gurus want you to believe in.
Depending on your site’s setup you might have the feature of user registration enabled (WP Admin > Settings > General). If you do, everyone who visits your site can register for an account. As always, it’s your job to convince people to register, but that’s not the point here.
The Email Users plugin gives you the possibility to contact your registered users directly via email. It provides a kind of email newsletter tool built into WordPress.
Also, users can send emails to each other, and power users can send emails to groups of users.