Hello,
I'm currently using this powerful toolkit for removing all unwanted subscribed ones like drug/sex bots and co from my phpBB forum :
http://starfoxtj.phpbbhelp.org/phpBB/toolkit/I think this toolkit can be used by a PellesC MOD here to clean about 40% of subscriptions here, those 40% represents bots of any kind and spammers !
Share this toolkit as much as possible, it's really powerful and efficient !