Once upon a time I used to run a site that hosted a long list of publicly available news servers. I closed that site down a few months ago because the work involved in maintaining it was too great. Well, I'm pleased to say that it's back and better than before. It now checks the servers on a regular schedule so they're guaranteed to work. So if your ISP doesn't carry the mozilla newsgroups or alt groups try one of the servers at usenet.startshere.net, which is the first part of the Usenet area of StartsHere.