General :: Use RANDOM Number In Procmailrc?

I want to generate random name for email file name to prevent overwriting but $RANDOM ENV VARs does not work in it what can I do? this is my procmailrc:

Quote:

SHELL=/bin/bash
SUBJECT=`formail -xSubject:`
FROM=`formail -xFrom:`
SUBJECT=`echo $SUBJECT | sed -e 's/ /-/g'`
FROM=`echo $FROM | sed -e 's/.*<//g' | sed -e 's/>//g' | sed -e 's/@/AT/g'`
STOREFILE=20`date +%y-%m-%d_%H-%M-%S`_${FROM}_${SUBJECT}_${RANDOM}${RAMDOM}

it works fine except ${RANDOM}${RAMDOM} and I do not want to use mktemp command .