Granted, qmail isn't maintained. (And if you want to comment
negatively
on its quality, I shall offer not one word of disagreement.)
But isn't that all beside the point? Surely exactly the same
IP/licensing problems would still apply if djb were to release a new
version tomorrow.
If QMail was actively maintained the license issues would be
exactly the same as for any other mailer. The problems come
from the fact that the mailer is abandonware and the license
prohibits any other party taking it on.
I would not waste my time maintaining QMail, I would replace
it wholesale or use one of the many other fine mail systems
out there.
Phill