as a result this no longer uses it's own tmpnam(3) but libc one
this also broke in a spectacular way when the strcpy/strcat/sprinf
userland warnings were used
real name, fchmod to 0644. Otherwise we end up with queue files and
the index file mode 0600 which is not the intention.
The original GNATS code makes queue files mode 0664 which seems excessively
open; 0644 should be fine.