question on scoring

Would something like this work for keeping someone from mailing you more
than 9 times in a day?

FROM=`$FORMAIL -zrx To:`
DATE=`date +%m%d%y`
LOG=$PMDIR/$DATE.log
NUM=`grep -c $FROM $LOG`

:0
* -9^0
* $NUM^0
/dev/null

I'm interested in whether this would work, and if it would be more
resource friendly than some of the other methods that have been posted to
the list for handling this.  

TIA

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