Find spamming account in Postfix or Plesk

Queue Counting
The following command provides a sorted list of the accounts that have the most mail in the queue. This usually means a maximum of 2 or 3 spammers at the end of the list:

mailq|grep ^[A-F0-9]|cut -c 42-80|sort |uniq -c|sort -n|tail

grep “status=sent” /var/log/maillog |cut -d “=” -f 2 |cut -d “>” -f 1 |cut -d “<” -f 2 |sort -n |uniq -c

grep “dovecot” /var/log/maillog |grep “Aborted login” |cut -d “,” -f 3 |cut -d “:” -f 4 |sort -n |uniq -c