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 314,368 websites that are WP-SpamShield Anti-Spam Customers. We know of 109,022 live websites using WP-SpamShield Anti-Spam and an additional 205,346 sites that used WP-SpamShield Anti-Spam historically and 66,454 websites in the United States.
Get a list of 314,368 websites using WP-SpamShield Anti-Spam which includes location information, hosting data, contact details, 137,917 currently live websites which includes 28,895 domains that redirect to sites in the list. 205,346 sites that used this technology previously and 66,454 websites in the United States currently using WP-SpamShield Anti-Spam.