Like any other piece of software (and information generally), qmail-conf comes with NO WARRANTY.
qmail-conf works only under UNIX.
As instructed below, you have to download the djbdns package and unpack it into some directory, but you don't have to install djbdns. Installing qmail-conf won't interfere with any existing DNS software installation.
Download the qmail-conf package. The latest published qmail-conf package is qmail-conf-0.60.tar.gz.
Download the djbdns package. The latest published djbdns package is djbdns-1.05.tar.gz.
Unpack the qmail-conf package and switch to the qmail-conf source directory:
gzip -dc qmail-conf-0.60.tar.gz | tar xf - cd qmail-conf-0.60
Edit conf-* files if necessary.
Unpack the djbdns package:
gzip -dc ../djbdns-1.05.tar.gz | tar xf -
Create Makefile, specifying the djbdns source directory (created in the previous step) with the djbdns=dir argument:
make -f Makefile.ini djbdns=./djbdns-1.05
Compile the qmail-conf programs:
As root, install the qmail-conf programs under /var/qmail:
make setup check
Make sure to include /var/qmail/bin in $PATH for root. Alternatively, you may prefer to create symbolic links in /usr/sbin that point to the qmail-conf programs:
ln -s /var/qmail/bin/qmail-*-conf /usr/sbin
Now you can set up a qmail delivery service, a qmail SMTP service, a qmail POP3 service, a qmail QMQP service, and a qmail QMTP service.