Postfix. 1 domain using multiple ip addresses for balance load

[GasDiver Dude]

Hi there Ladies and Gents

I wld like to setup a postfix server to send from 1 domain attached to many ip addresess.
Sending from many different domains each with single attached IP is no problem and i have achieved this using sender_dependant_transport_maps .

Now I wld like to attach 5 ipz to the same domain abc.com

Transport is listed in mysql and domain transport is to follow the entry in master.cf ... with abc-com-out:

The single domain is listed in master.cf as follows ...

10.20.30.40:smtp inet n - n - - smtpd
-o syslog_name=postfix-mail.abc.com
-o smtp_helo_name=mail.abc.com
-o smtp_bind_address=10.20.30.40
-o myhostname=mail.abc.com


abc-com-out unix - - n - - smtp
-o smtp_bind_address=10.20.30.40
-o smtp_helo_name=abc.com
-o syslog_name=postfix-abc.com

abc-com-out unix - - n - - smtp
-o smtp_bind_address=10.20.30.50
-o smtp_helo_name=abc.com
-o syslog_name=postfix-abc.com

abc-com-out unix - - n - - smtp
-o smtp_bind_address=10.20.30.60
-o smtp_helo_name=abc.com
-o syslog_name=postfix-abc.com


Now THIS is my problem ... it all works fine, except that postfix is always running through the list and always chooses the last ip in the last entry.

I know its possible to set up a random query from mysql so i can balance the load randomly , however what i wld like is to send and CHOOSE the ip to send from .

Mysql will not allow me to set a duplicate entry for something like ...


10.20.30.40:smtp inet n - n - - smtpd
-o syslog_name=postfix-mail.abc.com
-o smtp_helo_name=mail.abc.com
-o smtp_bind_address=10.20.30.40
-o myhostname=mail.abc.com


1-abc-com-out unix - - n - - smtp
-o smtp_bind_address=10.20.30.40
-o smtp_helo_name=abc.com
-o syslog_name=postfix-abc.com

2-abc-com-out unix - - n - - smtp
-o smtp_bind_address=10.20.30.50
-o smtp_helo_name=abc.com
-o syslog_name=postfix-abc.com

3-abc-com-out unix - - n - - smtp
-o smtp_bind_address=10.20.30.60
-o smtp_helo_name=abc.com
-o syslog_name=postfix-abc.com


there must be a way and im nearly sure the above worked flawless until i reboot the server and postfix kept choosing the last entry as opposed to what smtp is chosen by the sending client.

pre-thanks-to replies :)
thanks