Spam users registration despite of recaptcha

[ctgraham]

See also:

No logging for user validation emails?

Hi, @drbauder. When I initially implemented ReCAPTCHA v2 for OJS 2.4.8, I didn’t cover the use case of notification list subscriptions and I inadvertently broke (the now unusable) ReCAPTCHA v1. This was fixed in the patches @asmecher references. Unfortunately, ReCAPTCHA alone will not stop all spam registrations. We’ve found several instances of botnets (or distributed mechanical turks?) targeting specific journals we host of publish. These registrations are completing the ReCAPTCHA challen…