Spam is on the roll over @ my site
They are starting to bypass both recaptcha and custom profile fields. Any tips?
From reading this thread, it sounds like spam bots are programmed for standard phpbb captcha devices. Custom profile fields just only work until a bot owner feels your forum is worth the effort to write some exception code to handle your custom profile field.
Earlier in this thread, I liked the suggestion to ask math questions like "Sally bought 4 oranges and 3 tangelos, if she gave away two, but bought 4 more, how many does she have?"
There's also a math plugin which displays math as an image.
And, something that orients images, asking the user identify which two images are oriented vertically.
If you change the verbose math questions frequently, and the library of oriented images, I don't see how a bot could beat those. If you use 2-3 of those together....
But, I still think there's a risk of bot owners paying cheap offshore labor to register accounts at your site which the bot owner then uses for spam. Then you have to use the above captcha devices on posting screens too. Or, use the "newly registered user" restriction which puts a new-user's first 5-20 posts on review.
That, or use Akismet (or Spam Karma II) for "newly registered users" to try and catch spammy posts if you don't want to review new-user posts.