How to prevent spam in phpBB3
Here are some suggestions on how to protect from spam your phpBB3 board:
- Keep disabled guest posting. By default, the forum permissions are set to allow guests only to read the topics and not to reply to posts. If it's important for you to allow guests to post, make sure that CAPTCHA (visual confirmation) is enabled for guest posting.
- Check to make sure that CAPTCHA is enabled for new registrations. It's enabled by default. Make sure it stays that way. From the Spambot countermeasures settings of the admin panel you can also make the CAPTCHA image more difficult to recognize, so that it is more difficult for spam bots to register.
- Enable account activation from the User registration settings of the admin panel.
- Add extra fields to the registration form. You can do this from the admin panel: Users and Groups tab>Custom profile fields.
- Install anti-spam MODs. You can find some in the modifications database of the official phpBB site.
For some more details you can check the phpBB3 Spam Protection Tutorial.