that sounds like a lot of work…

From alpine‘s alpine-2.00/alpine/mailcmd.c:

                switch(r = is_writable_dir(dir)){
                  case 0:               /* exists and is a writable dir */
                    /*
                     * We could figure out if it is empty and use it in
                     * that case, but that sounds like a lot of work, so
                     * just fall through to default.
                     */

                  default:
:
case 3:               /* doesn't exist, that's good! */
: