Created a really ugly cron to check PPPoE-Connection status which runs every minute. This script produced over 500+ E-Mails in my Maildir.
This command will do the dirty cleaning job and let your fingers relaxed;)
Go to the users Mailbox:
Search a string from E-Mail and remove this E-Mail/s:
rgrep "monitor-pppoe.sh" * -l | xargs -n 100 rm