Praveen a11n

This plugin will send an email out to the administrator of the WordPress site to confirm and check if the server is able to send out an email
In future this plugin will also provide a whole suite of checks for other things.

Server Mail Check

This plugin will send an email out to the administrator of the WordPress site to confirm and check if the server is able to send out an email

Mammothology

WP Valid Email is a WordPress plugin which offers suggestions to users who mis-type their email address when entering it on your website. This is a common problem and can lead to loads of missed subscribers and customers.
WP Valid Email will offer suggestions for the most popular domains and the user can simply click the suggestion to replace the mistake. You can also enable email suggestions on the WordPress login form (wp-login.php) which 
should minimize support queries and forgot password requests significantly.
The plugin is fully customizable and will work on any form, even gravity forms and other form builders. You can also customize the appearance of the suggestion message to fit in with your own website style.
Features:
<ol>
<li>Automatically correct user email input mistakes</li>
<li>Can suggest all popular domain names & easy to add more</li>
<li>Choose any form fields to check for valid emails</li>
<li>Easily customize the appearance of the suggestion message CSS</li>
<li>Check WordPress login form as well</li>
</ol>
With thanks to the guys at Kicksend for their awesome open-source jQuery mailcheck code.
Video Example:
<iframe loading="lazy" title="WP Valid Email - Improve Your Website Sign-Up Rate" width="750" height="563" src="https://www.youtube.com/embed/Z9vSoz7GmPs?feature=oembed" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture; web-share" referrerpolicy="strict-origin-when-cross-origin" allowfullscreen></iframe>
<h3>Support</h3>
We offer limited support via our <a href="http://mammothology.com/forums/" rel="nofollow ugc">Support Forms</a>.

WP Valid Email

WP Valid Email is a WordPress plugin which offers suggestions to users who mis-type their email address when entering it on your website.

Server Mail Check vs WP Valid Email