Where can I get old postings to news:gnu.emacs.help and other GNU groups?
The FSF has maintained archives of all of the GNU mailing lists for many years, although there may be some unintentional gaps in coverage. The archive is not particularly well organized or easy to retrieve individual postings from, but pretty much everything is there. The archive is at ftp://lists.gnu.org/. The archive can be browsed over the web at the GNU mail archive.