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.

tornevall

Tornevall Networks DNS Blacklist support. Blocks comment functions or redirects visitors who is blacklisted to external site. 
Tested with WPCF7 5.1.4 (v2.0.8).
<a href="https://tracker.tornevall.net/projects/DNSBLWP/issues" rel="nofollow ugc">Project tracker</a> – Contribute with suggestions or bug reports here! 
<a href="https://wordpress.org/plugins/tornevall-networks-dnsbl-implementation/" rel="ugc">Plugin URL</a>
<h4>Contribute</h4>
Can you help? Register and join the <a href="https://tracker.tornevall.net/projects/DNSBLWP/issues" rel="nofollow ugc">project tracker</a> and start creating! 
You can also join the open source project at <a href="https://bitbucket.tornevall.net/projects/WWW/repos/tornevall-wp-dnsbl/browse" rel="nofollow ugc">Bitbucket</a>.
Want to add a new language to this plugin? You can contribute via <a href="https://translate.wordpress.org/projects/wp-plugins/tornevall-networks-dnsbl-implementation" rel="nofollow ugc">translate.wordpress.org</a>.

Tornevall Networks AntiSpam and Fraud Blacklist (DNSBL w/FraudBL) implementation

Tornevall Networks DNS Blacklist support for Wordpress

Geek Mail Blacklist vs Tornevall Networks AntiSpam and Fraud Blacklist (DNSBL w/FraudBL) implementation