Greetings, I have several Postfix implementations successfully handling outbound mail relay directly to the Internet. These servers handle mail individually; one physical server relays for all outbound mail for domainA.com, another for domainB.com, etc. All servers have DNS/rDNS set up properly so that they may do this.
I would like to consolidate all of these servers into a single Postfix mail relay server implementation. There is no need at this time for Postfix to listen for any mail, it will purely be used as a mail relay. The idea would be to have several IP addresses configured on the DMZ-facing NIC (10.1.1.0), and several IP addresses configured on the Internet-facing NIC (5.5.5.0). Mail originating from domainA.com would be sent to IP address 10.1.1.5 on the mail server and thus would be sent to the Internet out 5.5.5.5. Mail originating from domainB.com would always be sent to 10.1.1.6 and thus would be sent to the Internet out 5.5.5.6. The reason I would like it this way is so that outbound mail preserves hostname/domain information in headers for each individual company. Is this possible thru a single instance of Postfix? If so, what areas of configuration should I be concentrating on? Or should I be considering multiple instances? Thank you.
