Anti-spam by Author: webvitaly..
Anti-spam is a comments only anti spam plugin. It is automatic and invisible for users and for admins.
There is no captcha, no moderation queues and no settings page.
You just install it and it just works, EXCEPT:
It is incompatible with:
Disqus
Jetpack Comments
AJAX Comment Form
bbPress
WordPress Details Page: https://wordpress.org/plugins/anti-spam/
Compatible up to: 4.7
Active Installs: 100,000+
Release Date: 2012-09-06
3 ONE Star Reviews
110 FIVE Star Reviews
Author: webvitaly
Notes:
Anti-spam plugin blocks 100% of automatic spam messages (sent by spam-bots via post requests).
Plugin does not block manual spam (submitted by spammers manually via browser).
You can use Anti-spam Pro plugin ($15) if you need to block manual spam.
I tested this on a site using Jetpack Comments, and it blocks all comments as spam.
60.1 - 862,207