Radek Mezulanik

This plugin:
<ol>
<li>
Add 3 hidden fields to Registration form and to Comments form, that only robots can see. Plus you can choose to add validation checkbox to forms.
</li>
<li>
Add to .htaccess file direct access protection for comments file.
</li>
<li>
Check time user spent on page and time when user send a form.
</li>
<li>
Disable trackbacks for past and future posts.
</li>
</ol>
Additionally you can choose to add validation checkbox to forms.

Antispam Revolution

Three way antispam protection for registration and comment forms.

Till Krüss

A lightweight plugin that protects plain email addresses and mailto links from email-harvesting robots, by encoding them into decimal and hexadecimal entities. Has an effect on the posts, pages, comments, excerpts, text widgets and other filtered content. Works without JavaScript — just simple spam protection.
To see whether all your email addresses are properly protected, use the free <a href="https://encoder.till.im/scanner?utm_source=wp-plugin&utm_medium=readme" rel="nofollow ugc">page scanner</a> tool.
Other content (like phone numbers) can be protected using <code>[encode]</code> shortcode:
<pre><code>[encode]+1 (555) 123-4567[/encode]
[encode link="tel:+15551234567"]+1 (555) 123-4567[/encode]
</code></pre>
<h4>Premium Features</h4>
<ul>
<li>Full-page protection that catches all email addresses</li>
<li>Hardened protection using JavaScript and CSS techniques</li>
<li>Improved phone number protection</li>
<li>Built-in plugin support for ACF, Jetpack, WooCommerce and many others</li>
</ul>
Check out the <a href="https://encoder.till.im/download?utm_source=wp-plugin&utm_medium=readme" rel="nofollow ugc">Premium</a> version of Email Address Encoder.
<a href="http://coderisk.com/wp/plugin/email-address-encoder/RIPS-r0bJqKvBws" rel="nofollow ugc"></a>

Email Address Encoder


This might work with page or post content, but does not with widgets. I can't recommend using this and suggest to use the plugin "Email Encoder" by Jannis Thuemming instead, since that does the job out of the box.


Not working with widgets

A lightweight plugin that protects email addresses from email-harvesting robots, by encoding them into decimal and hexadecimal entities.

Antispam Revolution vs Email Address Encoder