The opendir() call fails, because the kernel returns a 'Permission denied' (EACCES) error condition.
Check the permissions of / /var /var/spool /var/spool/postfix /var/spool/postfix/defer Except for the last directory, all above directories must have read and execute permission for everyone. drwxr-xr-x 23 root wheel 512 May 17 2016 / drwxr-xr-x 25 root wheel 512 Mar 2 2016 /var drwxr-xr-x 9 root wheel 512 May 1 2011 /var/spool drwxr-xr-x 19 root wheel 512 Dec 25 2013 /var/spool/postfix drwx------ 18 postfix wheel 512 Aug 18 2011 /var/spool/postfix/defer Wietse