First of all, hello to all! I've searched google and forums and I've found tons of problems/solutions/threads regarding this problem, but none of them was solution to my problem or I'm doing something wrong. So for start, this is the my actual problem: # cat /var/log/mail.log | grep "[email protected]" Log is full of this kids of errors. Please note that: - all mailboxes are created from ISPConfig itself - this problem occures only for one e-mail address - e-mails are not received - there is no spam filter activated on any created mailbox - whole /var/vmail is chown recursively vmail:vmail Result from: # ls -la /usr/bin/maildrop # grep vmail /etc/passwd Folder for this account has path like this (and other email accounts also): ISPConfig -> System -> Server Config -> server -> tab "Mail": Server was install through this tutorial: http://www.howtoforge.com/perfect-server-debian-squeeze-with-bind-and-courier-ispconfig-3-p3 My /etc/postfix/main.cf: And /etc/postfix/master.cf: If there is anything else that could help with finding solution, please let me know. Thanks in advance to all.