I have at least two web servers which utilise Postfix to send mail from web applications. One is what I call the 'master' which will remain static and the other is what I call the 'slave', which is cloned often for load distribution. Each clone is given a random external IP. All of the servers are on a private IP range of 192.168.x.x to talk to each other.
I have a requirement to send mail via a particular SMTP relay from a client but an IP is needed for firewall rules. The issue is that I can't guarantee the IP of the servers except for the 'master'.
Is there a way I can direct mail from the 'slave' servers to the 'master'? Ideally, the master will then route mail to the SMTP relays that are set up for each domain.
Thanks