Hi Folks, while using ISPconfig for quite a long time i was confronted with the fact of growing files within the /var/spool/mail directory. I think this happens because postfix accepts mail for every system user which is the normal behaviour?! So even when postfix is configured to accept mail only for "valid email users" that are mapped via virtusertable to "real system users", emails for the Linux "default users" like nobody uucp or mail are accepted and delivered. One solution to this is to reject those unwanted mails using smtpd_recipient_restrictions defined within main.cf. Adding there "check_recipient_access hash:/etc/postfix/denied_recipients" before the "permit_mynetworks" statement allows you to reject those unwanted mails. After adding them to this file (one address per line) in the form of [email protected] don´t forget to run postsuper /etc/postfix/denied_recipients and restart postfix. On my systems i am using Debian Etch and perhaps there are other ways to achieve this, but for me it did the trick.