If you are being harassed or threatened, you need to report the person. Do not use The DIS Moderators PM box...it doesn't work.
A couple of ideas...
1) *Directly* contact (either by PM or e-mail) the Mods for the forum where this is happening.
2) Keep all PMs & all e-mails, you can even download them to your own computer. DO NOT DELETE the offensive material.
3) I know that entire threads can be locked and individual posts can be deleted, but anything like that has to be done by a Webmaster (or a Mod). If a thread is locked, then it will just fall off the first page and drift into oblivion.
4) I don't know if another DIS'er can be blocked from PM'ing you, but you can put other DIS'ers on "ignore". Then at least you won't have to see their posts.
5) If someone is being rude, sarcastic, using personal attacks and they are posting this stuff in a thread, report the individual post. Just go down to the bottom left hand side of the offending post. There will be a triangle with an exclamation point in it - click on that, and follow the instructions.
If you need any other ideas, feel free to PM me.
Good luck,
agnes!