Like a mailing list, a newsgroup operates like a forum with people adding running commentary to the various subjects under discussion. But with a newsgroup, you have to be proactive to get the information, and your emailbox isn't filled with daily postings. Most new versions of web browsers will read newsgroups. There also are special websites that handle news, conveniently categorizing the various groups by subject. If you become active on a newsgroup, you'll also find many networking opportunities.
Producers occasionally announce their needs on newsgroups as well.
If you can't find a newsgroup that focuses on your special interest, there is a process by which you can begin your own net-supported newsgroup. See the links in the self-guided tour . These different sites all have something to offer the beginning screenwriter, some more, others less, and I recommend that you check them all out. When you find the sites that offer what you are looking for, return often because the best sites frequently update. My site, for example, is updated almost daily.