There are three mailing lists relating to Xapian:
The [Gmane] links take you to the Gmane news gateway which allows you to read these list with a newsreader, or browse the archives on the web.
Posts from non-subscribers currently require approval (we'd rather not have to impose this restriction, but we also want to avoid relaying spam to our subscribers). So if you aren't subscribed, there's likely to be a delay before your message is approved and relayed to the list.
We don't currently have a dedicated announcements list. If you just wish to hear when new versions become available, you can "subscribe" to release announcements via the Xapian project page on freshmeat. New releases are announced there and on xapian-discuss.