Recently we had to spend some time on fighting email spammers, who used “Share” function of Checkvist to send emails with hand-crafted “share note”.
The summary of what worked for us is here: http://blog.checkvist.com/post/166940442968/how-to-stop-spammers-and-not-impair-the-good
What did not work:
Maybe our experience will be useful to some of the people here
So email verification and reCAPTCHA?
Spammers can verify the source emails, can’t they?
And reCAPTCHA… I do not really know how it works, but I recently heard a neural network was trained to work around reCAPTCHA.
So… do not relax as of yet.
I hope they have not yet worked around invisible reCAPTURE as of 2017.
When this reCAPTURE is unsure if you’re a human you should identify some objects on several pictures. I don’t think it can be solved by IA yet. It may be cheaper to hire some poor mechanical turks to pass the capture than to use IA.