Evan Solomon

When you click links, your browser sends referrer information to the site you land on. This is how you get things like referrer counts in Google Analytics. Sometimes, though, you don’t want people to know where you clicked their links from. By default, this plugin will hide your referrers for links from <code>wp-admin</code>. You can also use it to hide links on the front end of your site by making a plugin along the lines of this.
<pre><code>add_action( 'wp_enqueue_scripts', 'es_anonymous_admin_links' ); </code></pre>

Anonymous Admin Links

Hide the referrer for external links in wp-admin using href.li

nicholas_tsim

Add useful referrer information to emails sent via any Contact Form 7 contact forms on your WordPress website. Based on the Enhanced WordPress Contact Form plugin by Yoast.
Main features are: 
* Add website referrer(s) links. 
* Pages visited on your website. 
* Search engine keywords used (if referrer was a search engine).
<h3>Notes</h3>
Can be modified to only replace [referrer] tags by uncommenting line 148 and commenting line 150. May be useful if you want to restrict which contact forms send referrer information and which don’t.

Contact Form 7 Referrer Addon Plugin

Add useful referrer information to emails sent via any Contact Form 7 contact forms on your Wordpress website. Based on the Enhanced Wordpress Contact …

Anonymous Admin Links vs Contact Form 7 Referrer Addon Plugin