Asking people with phpBB experience, the main things you need are:
1. captcha or similar for account registrations
2. moderate all registrations that make it past that
3. mods who like phpBB forums and catch and block as needed the people
who make it past that.
Some moderation on the gateway to the list would be useful as well.
I use Akismet on my WordPress blog and it's fantastic. There's a phpBB port:
http://www.eadz.co.nz/blog/article/phpbb-akismet.html
- though I know that a lot of wine-users posts get caught by my
various spam filters (presumably because there's so much spam for
warez copies of Windows programs), so I'd review and train it
carefully.
Various other ideas:
http://forums.digitalpoint.com/showthread.php?t=57141
http://boonedocks.net/mike/archives/49-PHPBB-Member-List-Link-Spam.html
http://boonedocks.net/mike/categories/9-PHPBB
http://www.phpbb.com/community/viewtopic.php?t=427852
(I am not volunteering as a mod myself!)
- d.
