Now I tried myself and found that everytime I enter the requested letters / digits, I get new captchas and the text says: "You did not pass the anti-spam tests. Please check if you entered the CAPTCHA correctly." (I really think I did)
Then I looked in the admin-interface at "spamblock bayes" and found my attempts in the spam. Maybe it was not a good idea to use the nick "test3"
Is there a way to protect the user-registration from too much abuse and still make it work? (I used to run it withough spam-protection for a long time, but started getting several dozens of abusive registration attempts every day, so I turned on "use captchas")
What really amazes me is why I don't find the attempts in my apache-log.
I am using s9y 1.6.2, Spam Protector and Spamblock Bayes are installed.