Errormessage in maillog - empty query string

[ispconfig_question]

I have found following errormessage in my maillog:

postfix/smtpd[36719]: 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/allge...-ignored-3902/
It is 5 year old and have no conclusion, so I thought to ask again.

My mysql-virtual_client.cf contains this:

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.

[till]

Most likely a header in the email that you sent with php is missing. This isnt critical, so I would ignore it if you dont want to change your php script.

[ispconfig_question]

Thaks for the answer. Could you please be more specific about which header could be missing? I don't mind to change the PHP script at all, actually I'd like to improve it if possible.

[ispconfig_question]

Could you please write me more about the missing header? Which header could it be? I would like to correct the PHP app so that it won't cause these errors...