Yes, but almost all of that has been making the build scripts compile at all on recent systems. Nobody actually wants to touch the ancient apps that are included.
I would be surprised if anyone would want to fix up the likely spaghetti code that is the mail app and write all the functions that became standard in the last 30 years. You'd basically end up with either a thunderbird clone or something that is almost as useless as what we have right now.
I wish someone would actually release the maxx desktop sources. Or that a developer fixed up olvwm, which has been abandoned on every distro for some years.