Capably Digital's Email Validation and Blocklist plugin blocks spam signups and cuts WordPress bounce rates with local MX checks — no per-lookup API fees.
Researched and fact-checked by Bartu Cavusoglu · Updated October 16, 2026
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Capably Digital Email Validation and Blocklist is a WordPress plugin built by UK-based Capably Digital LTD that hooks directly into WordPress's native email functions (`is_email` and `pre_wp_mail`) to stop invalid or unwanted email addresses before they reach a form submission, user registration, or outgoing email. Instead of relying on a paid third-party email-verification API charged per lookup, the plugin checks addresses locally against an editable blocklist of emails and domains and validates MX records to confirm a domain can actually receive mail, with an optional A-record fallback in the Pro tier.
Site owners can run the plugin in monitor-only mode first to log activity and check for false positives before enforcing any blocking, then choose a strictness setting for how unparsable addresses are handled. The plugin is built for multisite WordPress networks (each site manages its own independent blocklist and settings) and for larger installs: the vendor states it has been tested against blocklists of more than 250,000 domains on basic shared hosting. Developers can lock down configuration via `wp-config.php` constants and extend behavior through exposed hooks, with published documentation for both.
The free version (available on WordPress.org) covers the core blocklist, MX checking, monitor mode, strictness control, external list synchronization on a schedule, logging, and multisite support. Capably Digital Email Validation and Blocklist Pro — purchased and license-managed through the vendor's own site and activated from inside the WordPress dashboard — adds a configurable default allow/block action for addresses not on any list (useful for self-service member registration), deeper email validation (parent-domain checks, plus-addressing collapse, minimum length rules), the ability to sync and combine multiple remote lists including whitelists, A-record fallback checking, email 'scrubbing' that strips only the invalid recipients from a multi-recipient send, finer-grained and anonymizable logging, automatic log deletion to help with data-protection compliance, and a front-end shortcode to show blocked users a status message outside of wp-admin.
Capably Digital LTD (company number 17002898, registered in England and Wales) also sells adjacent web services — custom WordPress plugin development, web development, web hosting, and site maintenance — as quoted, project-based work, but the Email Validation and Blocklist plugin itself is sold as a standalone, self-serve, tiered-pricing product with its own purchase flow and customer licence portal, separate from that bespoke services business.