I haven't read every post above, but in reflecting the sentiments of many of you:
The general guidelines for open forum posting apply equally to private messages using the JWD p/m. Therefore, if someone is violating those guidelines, notify a mod and, indeed, there are ways of at least eliminating that particular account, as the circumstances warrant.
Unfortunately, it is most often the case that these nut-jobs just set up another account, and continue on with their venom. The only resort is to notify a mod accordingly, at each occurence.
However, as tempting as it is to exact a degree of revenge against such vicious Internet savages, it would be counter-productive to post up any private messages or e-mails, both because it gives them the attention they don't deserve, and also because posting such private communications without the specific permission of the sender (as vile as that sender might be) is also a breach of open forum protocol.
All that being said, I fully share the anger and frustration that you all have expressed, and can't tell you how many times I've had to push the "delete" button on my angry response posts...though I certainly haven't been perfect at that effort of self-control, and have more than a few times had to have my own posts edited.
Respects,
Craig
edit to add: I think it was Ang who last edited one of my last "errant" posts...when I saw what she had done, I chuckled and said to myself: "Well, Craig, you rather deserved that, didn't you?" LOL