Mailing list mode: support for creating topics?

Thanks to @encukou for explaining “mailing list mode” to me and encouraging me to give it a try and see if it’s more usable for me than the web UI. One thing I noticed is that by default mailing list mode only seems to help for replying to an existing topic. Creating your own topic is apparently supported by the software but has to be manually enabled in the admin settings and configured with an email address to accept new threads on. Would it be possible to support this?