I have been using opensmtpd for fully dex operation, as described in https://fedoramagazine.org/decentralize-common-fedora-apps-cjdns/ (Yes the smtpd.conf has changed a bit since that article was written.)
Now, I wanted to also relay outgoing mail that is *not* a raw IP through a server. Using relay host is straightforward, but then I lose the fully dex operation. Is there any way to have my cake and eat it too?