How to stop spammers, and not impair the good customer experience


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:

What did not work:

  • blocking spammer IPs (they have plenty resources, really)
  • adding limitations by a number of sent invitations (they created different lists, different accounts, removed and re-created invitations)
  • avoiding sending many emails to a particular domain ( is the famous one).

Maybe our experience will be useful to some of the people here :slight_smile:



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.