Very occasionally we find an enterprising spammer trying to increase their income by spamming on this baord. They go through the entire registration process and then input four or five messages by way of URL references, generally to porn site.
 
Please, Please do not  access those sites if you see such a spam. We attempt to take them down the same day they appear. If no accesses are created from their efforts, they will soon realize that this site is not an income generator for them and they will cease to use it.
 
Thank you for you cooperation in eliminating this obscene intrusion on our otherwise very well used site.

lately 'newest posts' page is 90% spamm, something needs to be done, few thougths on the matter:
updateing YaBB to newest version(DO NOT FORGET BACKUPS DO NOT FORGET BACKUPS DO NOT FORGET BACKUPS DO NOT FORGET BACKUPS)
or/and manually modifying registration form so bots coulndnt handle it
user registration admin verification - it makes registering uncomfortable for new users, but forum overloaded with spamm is useless anyway
what e-mail adresses are the bots using to register their accs - if these are uncommonly used sites they can be banned, most people have g-mail, hotmail, yahoo or something of the like accounts, its a lot easyer to put up your own mail server and use it to reg spamma ccounts than it is to crack hotmail and gmail captchas
 
these measures should dramatically reduce amount of spamm on the forum, im sure there are even more effective measures that can be taken if needed, for starters applying few of these should do the job

why do you think its not bots?

great to hear that, tho if the source was confined to only one isp in china or even better one static ip it probably would have been better to just ban that ip(range) - temporary solution but manual reg makes harder for new members to sign up

I haved been moving the spamming to the trash bin so to speak so that the webmaster could do his tricks to discover the source. I am now deleting the remnant in the forum.

An unfortunate event. I am forwarding this complaint to our webmaster.