Second IP address.
Well I am going to try and add a new ipaddress so the postfix can use it to send emails.
Seems that the host gave me a block of IP addresses that are not doing well with Gmail/Yahoo bulk.
On one server without ISPConfig it was easy. I just changed the postfix settings so it would send from this new ip which is another subnet but really on the server of course.
Is it the same process for ISPConfig ie just edit /etc/networking/interfaces to show this eth0:3
Then /etc/hosts so it is in there.
Then /etc/postfix/main.cf as needed?