There are several spamming tools that can detect the built-in phpBB image verification during registration. In practice, enabling this has almost no effect on forum spam. A solution that would help (for a while) are registration questions that can only be answered by a human (quick math question, etc.), possibly by replying to the registration verification email in a pre-defined format.
There are several spamming tools that can detect the built-in phpBB image verification during registration. In practice, enabling this has almost no effect on forum spam. A solution that would help (for a while) are registration questions that can only be answered by a human (quick math question, etc.), possibly by replying to the registration verification email in a pre-defined format.