Qmail is a secure, reliable, efficient, simple mail transport system.
to build a binary deb package, first install the qmail-src package, then type the command "build-qmail". if you try "apt-get source --build qmail-src" only the qmail-src package will be built. you will need to install qmail-src and type the command "build-qmail" to get a usable binary package of qmail. also be sure to build and install ucspi-tcp before installing the binary qmail package. install the ucspi-tcp-src package to get ucspi-tcp.
this package builds a binary .deb that is fhs compliant and conforms to the debian standards guidelines. the resulting binary packages are not suitable for re-distribution.