Flexa Unsubscribe adds a complete unsubscribe workflow to every email WordPress sends, with a fully-branded admin UI for managing opt-outs, analytics, and the public unsubscribe page.

Auto-appends a secure unsubscribe button to outgoing single-recipient emails. Tokens are HMAC-signed using the AUTH_KEY in wp-config.php, so no database lookup is needed to verify a link.
Blocks outbound mail to unsubscribed addresses before it reaches the mail server. Blocked attempts are logged to a dedicated audit table.
Honours an exclude-keywords list (default: Order, Password, Invoice) so transactional mail never gets an unsubscribe link and never gets blocked.
Re-subscribe URL is supported as a first-class action – the plugin can tell opt-outs from opt-backs.
Customisable public page – every color, font, and string on the unsubscribe/re-subscribe templates is editable from the admin with a live preview.

All screens are powered by a REST API under /wp-json/flexa-unsubscribe/v1/, so external integrations can plug in too.

Documentation

Full user guide, technical reference, and REST API documentation are hosted at:

https://unsubscribe-doc.flexacommerce.com/

A “Documentation” link is also added to the plugin row on the Plugins screen for one-click access from inside WordPress.