I do not know what the other Linux distributions, but on Debian is a problem with the autoresponder. In the panel customer enable autoresponder system create files in the directory When new email arrives the system creates two files .vacation.lst.lock and .vacation.lst.gdbm Customer ISPconfig off the autoresponder but system can not delete these files because the file is maildrop_plugin.inc.php Code: $file = $this->mailfilter_config_dir.'/'.$email_parts[1].'/'.$email_parts[0].'/.vacation.lock'; $file = $this->mailfilter_config_dir.'/'.$email_parts[1].'/'.$email_parts[0].'/.vacation.lst'; and should be Code: $file = $this->mailfilter_config_dir.'/'.$email_parts[1].'/'.$email_parts[0].'/.vacation.lst.gdbm'; $file = $this->mailfilter_config_dir.'/'.$email_parts[1].'/'.$email_parts[0].'/.vacation.lst.lock';