The lfs-announce list is a moderated list. You can subscribe to it, but you can't post any messages to this list. This list is used to announce new stable releases. If you want to be informed about development releases as well then you'll have to join the lfs-discuss list. If you're already on the lfs-discuss list there's little use subscribing to this list as well because everything that is posted to the lfs-announce list will be posted to the lfs-discuss list as well.