CFLAGS="-g -O2 -posix -ansi -Wall -Wtraditional -Wshadow -Wpointer-arith -Wcast-align -Wcast-qual -Wwrite-strings -Wconversion -Wstrict-prototypes -Wmissing-prototypes -Wnested-externs -Winline -ansi -pedantic" ./configure --prefix=/opt/mail --with-gcc --with-ipv6