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