Vishnu Supreet writing on WebHosting Secret Revealed has posted an interesting article “How to Stop Spammers On Your WordPress Site”
The article covers some Anti Spam Solutions both free and paid for, including: WP Spam-Shield Anti Spam, Antispam Bee, Akismet and Anti-Spam By Clean Talk.
CleanTalk is a cloud based service engineered to stop spam comments, spam registrations, spam mail via contact forms and spam created by trackbacks.
Anti-Spam By Clean Talk Download: https://wordpress.org/plugins/cleantalk-spam-protect/