GeekParadize

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.

Comments Word Blacklist Manager

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

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

Comments Word Blacklist Manager vs Tornevall Networks AntiSpam and Fraud Blacklist (DNSBL w/FraudBL) implementation