We have been dealing with a troll that has registered hundreds of times, even sends daily e-mails to our admins, it's a real nutcase. What we did:
* made our own troll mod --> worked for a while until he realized it
* ban after ban after ban, even complete ip ranges but easy to bypass
* let him be for a while
* deposit a complaint at the police
* deposit a complaint at his IPS
Nothing has worked so far, the troll still keeps popping up now and then, we keep deleting his posts when we find out.
There's just not really anything u can do about it, I'm afraid
. Apart from hiding all his posts, but IMO this should be quite easy to do... I might have a look at that.