Wagner

<ul>
<li>Block certain kinds of users from registering to your WordPress site by adding blacklist rules. </li>
<li>Super simple to use. The whole plugin just has one simple settings page.</li>
<li>Support regular expression rules.</li>
<li>Completely free.</li>
<li>Support tracking and recording login attempts since v1.1.0.</li>
<li>Login attempts chart since v1.1.0.</li>
</ul>


Geek Mail Blacklist

Block users with certain emails from registering to your WordPress site by adding blacklist rules.

GeekParadize

<p>Comment Word Blacklist Manager will retrieve a list of blacklist terms from a remote source and update the <code>blacklist_keys</code> setting in WordPress. The list will update itself on a schedule to keep your terms current. Any manually added items will be retained, and an exclusions list is also created if there are terms from the source you want to allow.</p>


Comments Word Blacklist Manager

Remotely add known terms into the WordPress blacklist keys to manage spam

Geek Mail Blacklist vs Comments Word Blacklist Manager