I think all CAPTCHA solving "services" that offer reCAPTCHA solving rely on human work, and thus work on a delay (which obviously is just a minor inconvenience

I think all CAPTCHA solving "services" that offer reCAPTCHA solving rely on human work, and thus work on a delay (which obviously is just a minor inconvenience for any mass spamming operation). Here's a pretty nice article about it.[1] ReCAPTCHA itself remains unbroken to date (and it sure has gotten harder over the years too). [1] http://www.troyhunt.com/2012/01/breaking-captcha-with-automated-humans.html http://www.troyhunt.com/2012/01/breaking-captcha-with-automa...