I have found following errormessage in my maillog: Code: postfix/smtpd: warning: table "mysql:/etc/postfix/mysql-virtual_client.cf": empty query string -- ignored System is ISPConfig3 on CentOS6.0 installed according to the perfect server guide. The error occurs everytime mail is sent from PHP app on localhost (and not for other mails). I have found the same issue in this thread: http://www.howtoforge.de/forum/allgemein-11/postfix-fehlermeldung-empty-query-string-ignored-3902/ It is 5 year old and have no conclusion, so I thought to ask again. My mysql-virtual_client.cf contains this: Code: user = ispconfig password = password dbname = dbispconfig table = mail_access select_field = access where_field = source additional_conditions = and type = 'client' and active = 'y' hosts = 127.0.0.1 I'm not sure whether there is something wrong or it is normal - the mails seems to be delivered correctly. But I would like to know the reason for the message to be sure. Thanks in advance for your help.