Ubuntu server. Need cron help

I have been trying to create a script to check the number of files in a directory and if the quantity of files exceeds the allowable amount the script will email the details to me. I have created a script that works fine when I execute it from terminal. If I let cron execute the script I will not receive the email of results when executed by cron. I can see the script being executed in the syslog by cron with no errors but I do not receive the email. I am new to writing scripts for Linux so please bare with me. The script checks to make sure there is no backscatter going on in email queue. The email usage is very low so 20 -30 emails an hour is a lot.

any help would be appreciated.

#!bin/sh
# checks if there are more then 40 emails in the spool and emails me if there are
count=$(ls -1 /var/spool/postfix/active | wc -l)
if [ $count -gt 40 ]
then
	SPOOL=/var/spool/postfix/; for dir in $(ls $SPOOL);do echo "$dir: $(find $SPOOL/$dir -type f |wc -l)"; done >> /tmp/spamspool.txt
	mail -s "WARNING: SPAM ATTACK in SPOOL" my-email@example.com < /tmp/spamspool.txt
	rm /tmp/spamspool.txt
fi