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 DNSBL and FraudBL protection for WordPress. The plugin helps block comment activity, account registrations and other unwanted submissions from addresses flagged by Tornevall Networks DNSBL and FraudBL.
FraudBL is part of the protection layer used by the plugin and is available at <a href="https://www.fraudbl.org/" rel="nofollow ugc">fraudbl.org</a>. For general discovery, broader search terms like fraud, blacklist, comment spam and user registration are usually easier to find than niche technical acronyms alone.
The plugin is intended to provide a lightweight anti-spam and anti-abuse layer for WordPress, with support for local caching to reduce repeated lookups and unnecessary load against blacklist services.
Current admin features include manual DNS lookup tools, self-check tools, visitor statistics, safe IP whitelisting, frontend dry-run support for administrators, Cloudflare Turnstile for comments, and DNSBL plus Turnstile protection for new WordPress account registrations. Tools integration now uses one visible DNSBL / Tools API token field in the plugin UI. The live Check token permissions flow always asks Tools directly, warns clearly when the token exists on the other Tools environment (<code>tools.tornevall.com</code> vs <code>tools.tornevall.net</code>), and reports the effective DNSBL permissions for the configured token. Active admin-owned Tools tokens are shown as having automatic DNSBL access through the same <code>X-Dnsbl-Token</code> transport. The plugin now also warns on the WordPress dashboard and settings page when the current token cannot perform live delete / delist operations yet, with a direct link to the active Tools access page. The token status area shows current add/delete/update capability instead of only saying that a token exists, and delisting-page controls stay read-only until delete / delist permission has been confirmed. Internal delist slug routing now uses a dedicated rewrite/query-var path and refreshes rewrite rules on activation and slug changes to avoid <code>/delist</code> 404 cases. The managed public delist page now runs as a checker-style IP-only flow (checks listing first, then submits delist), while custom shortcode pages still support the broader permission-aware operations. The plugin also ships a shortcode delisting/removal form (<code>[dnsbl_removal_form]</code>) with AJAX backend proxy and optional API dry-run acknowledgement, plus a built-in primary removal-page template that is only activated when the configured token has live delete permission.
Report issues and feedback: <a href="https://github.com/Tornevall/tornevall-wp-dnsbl/issues" rel="nofollow ugc">GitHub issues</a> 
Plugin URL: <a href="https://wordpress.org/plugins/tornevall-networks-dnsbl-implementation/" rel="ugc">WordPress.org plugin page</a> 
Documentation: <a href="https://tools.tornevall.net/docs/dnsbl-api" rel="nofollow ugc">DNSBL API documentation</a>
<h4>Support and feedback</h4>
Bug reports and feedback can currently be submitted via <a href="https://github.com/Tornevall/tornevall-wp-dnsbl/issues" rel="nofollow ugc">GitHub issues</a>.
Full Documentation: <a href="https://tools.tornevall.net/docs/dnsbl-api" rel="nofollow ugc">DNSBL API documentation</a>
Translations can be contributed via <a href="https://translate.wordpress.org/projects/wp-plugins/tornevall-networks-dnsbl-implementation" rel="nofollow ugc">translate.wordpress.org</a>.

Tornevall Networks DNSBL Implementation

Tornevall Networks DNSBL implementation with FraudBL support for WordPress

Geek Mail Blacklist vs Tornevall Networks DNSBL Implementation