Let's install it...
cd /downloads/qmailrocks
tar zxvf maildrop-1.6.3.tar.gz
cd maildrop-1.6.3
./configure --prefix=/usr/local --exec-prefix=/usr/local --enable-maildrop-uid=root --enable-maildrop-gid=vchkpw --enable-maildirquota
make && make install-strip && make install-man
If you didn't get any errors, maildrop should be all set!