Jacques Malgrange

This plugin adds a simple widget that allows you to display an email form and a submit button.
<ul>
<li>You have the options to choose to recommend the site or the current page.</li>
<li>The mail subject and content can be changed.</li>
<li>You can limit the number of recommendation sended by user a day.</li>
</ul>
The widget is only displayed if the user is connected.

Recommend by mail widget

Recommend the site or the current page to a friend by mail.

spicethemes

This plugin allows you to add social share buttons to your posts. The plugin is flexible and easy to use.
<h3>Key Features</h3>
<ul>
<li>Supports Facebook, Twitter, LinkedIn, Email, Pinterest, WhatsApp, Print share buttons.</li>
<li>Typography setting</li>
<li>Color setting</li>
<li>To find the Typography And Color settings Go to Appearance >> Customize >>Spice Social Share>> Find the respective settings.</li>
</ul>
<h3>External Resources</h3>
Font Awesome 
Copyright: (c) Dave Gandy 
License: https://fontawesome.com/license ( Icons: CC BY 4.0, Fonts: SIL OFL 1.1, Code: MIT License ) 
Source: https://fontawesome.com
Customizer Sortable 
Kirki, Copyright © 2016 Aristeides Stathopoulos 
License: MIT License, http://www.opensource.org/licenses/MIT 
Source: https://github.com/aristath/kirki
Customizer Toggle Control 
Copyright: (c) 2016 soderlind 
License: Under GNU General Public License v2.0 
Source: https://github.com/soderlind/class-customizer-toggle-control

Spice Social Share

Effortlessly add social share buttons to your posts.

Recommend by mail widget vs Spice Social Share