With time, a little luck and some experience you may be able to "find" 
the person and find out something about him.  Sometimes threat of 
lawsuit or even just letting him know you "know about him" is enough to 
scare him away.  

In one case several years ago, I had one particularly nasty harasser 
that had started posting using his work e-mail.  I told him I would 
contact his employer if he did not immediately cease and desist 
harassing my list members.  He didn't and I called his boss.  I received 
only one more e-mail from him: "Why did you call my boss?!"   Amazing.   
But we didn't hear from the person again.

But that was an extreme case. Most aren't worth the effort.   Usually 
the "Default-Options= Review" methods are sufficient deterrence.

cheers, wayne