I tested this 3 times, obviously not on a massive scale. I opened gmail to create an email and it wouldn't take the captchas, they were 100% perfectly readable, tested this twice and it wouldn't take it. After that I decided OK, and this time I scrolled down the terms of service on GMail's website and each time it worked 100%. I think they are checking to see if you checked their TOS and if not they reject you a few times and then let you through. Test it and feedback. Btw: Not sure where to put this as it doesn't relate to anything really.