WordPress anti-spam plugin that eliminates comment spam, trackback spam, contact form spam & registration spam.
https://wordpress.org/plugins/wp-spamshield/
Widgets · WordPress Plugins
Get access to data on 313,847 websites that are WP-SpamShield Anti-Spam Customers. We know of 100,321 live websites using WP-SpamShield Anti-Spam and an additional 213,526 sites that used WP-SpamShield Anti-Spam historically and 60,437 websites in the United States.
Get a list of 313,847 websites using WP-SpamShield Anti-Spam which includes location information, hosting data, contact details, 100,321 currently live websites and an additional 50,508 domains that redirect to sites in this list. 213,526 sites that used this technology previously and 60,437 websites in the United States currently using WP-SpamShield Anti-Spam.