I have posted Fight against Spam, Spammer and Bots on PHPBB forum system.
I have Humanizer mod for PHPBB, and Hide User’s WebSite Button 1.0.3 on my forum to protect against spam.
Now I feel it is not enough. I clean the spam every day.
I found this one SpamWords.
It can prevent the spam post with the “spam words” I setup in the system in advance.
It is cool that when a spammer want to post some spam, he will receive the error message and he can not successfully post it.
If you want this plugin, you can Download file here.
It will add some tables in your PHPBB database, and modify some files and install some new files.
The difficult fact is medium.
It took me about 15 minutes to install it. Please backup all files and database before installation.