From wp-fail2ban-redux - check commenters

```php
add_action( 'comment_post', array( $this, 'comment_spam' ), 10, 2 );
add_action( 'wp_set_comment_status', array( $this, 'comment_spam' ), 10, 2 );
add_filter( 'xmlrpc_pingback_error', array( $this, 'xmlrpc_pingback_error' ), 1 );
```
https://github.com/thebrandonallen/wp-fail2ban-redux/blob/develop/wp-fail2ban-redux/classes/class-wp-fail2ban-redux.php#L99