SpamAssassin - Use this program to "Unspam" your mailbox(es).
WP Rocket - WP Rocket offers a caching plugin for Wordpress.
Rspamd - Rspamd is an advanced spam filtering system that allows evaluation of messages by a number of rules...
Yoast - Yoast offers plugins to improve SEO and optimize web sites and blogs.
Oikik Antispam - Oikik is a cloud-based email filtering service that works with your existing email service.
Wordfence - Comprehensive security plugin for WordPress.