I wondered that too. Certainly seems like fixing qmail to make it a little less rabidly user-unfriendly would be better than completely reinventing the wheel.
But kudos to them for going out and doing it anyway. I don't know if the world really needed one more MTA but it certainly won't hurt anyone.
For OpenBSD in particular, there's a history of arguments between djb and Theo about the licensing for qmail and djbdns. They're both incredibly stubborn, and while this means they have very high standards, it also means they can be hard to collaborate with.
I was thinking the same thing. I also wonder why more Linux distros do not include qmail. Other than having a few anachronisms, which can quickly be brought up to modern times, it's a fast, secure, time-tested, and completely respectable mail system.
Given that Postfix and Exim have much friendlier upstream developers (qmail barely has a maintainer), I don't think it's a surprise that qmail is losing popularity.
qmail itself is completely unmaintained and patches to it are actually rejected. net-qmail and others have sprung up to fill this void, but its got nowhere near the community surrounding it that Postfix does. Plus, qmail is very hard to use for someone just looking to send some mail, which is the common case (not the case qmail was designed for, either).
Someone should also mention that 'public domain' != free to use. Many countries don't recognize the public domain which means that many projects wont touch code in it. They would much rather have BSD or GPL code.
What I'm trying to say is that public domain has issues within the international realm. With something like the BSD license you declare very explicitly what you allow and I believe (if I understand correctly, I am not a lawyer) according to the Berne Convention that those explicit declarations work in an international realm.
So if your product is never going to be used/sold/shipped out side of USA, England, and a few other countries Public Domain is alright. Otherwise you need to use something like Creative Commons Zero License or a BSD/MIT License.
The Berne Convention is much too old to specifically address the bare licenses used for open-source software. However one of the provisions of the convention is that any creative work is protected under copyright law without requiring explicit registration. This creates a problem for declaring something in the public domain since there is not really an established legal procedure for a copyright owner to waive or forfeit the exclusive rights which have been automatically granted to them.
