a shell script of
cat /var/log/qmail/current | grep "from <WHOMEVER" | wc -l
will display the number of emails sent from WHOMEVER but there is nto time stamp that I can associate with the records, so it would be the number of emails sent since the log rotation to current.
The script can be fleshed out to mak a decision on the number of emails and send an email to admin if they match or exceed.