The image attached above is a reference for this discussion.
So I have a mail server hosted within the company corporate network. This server is hosting multiple mail domains using Hmail server mail server application running on a server @ 192.168.100.100 as shown above.
A records of the following domains are pointing to respective public static IP address as shown.
Port forward for SMPT and POP3 are configured on the 3 public IP addresses towards mail server inside.
Each of the ISP have provided additional public static IP address .2 and .3.
Note that mail.domain3.com has an A Record pointing to 184.108.40.206 that is additional static IP address on WAN2 interface.
What is the best approach of this case to make sure that;
mail traffic for mail.domain1.com will come in and go out on the same public static IP address 10.10.10.1?
mail traffic for mail.domain3.com will come in and go out on the same public static IP address 220.127.116.11?
mail traffic for mail.domain2.com will come in and go out on the same public static IP address 18.104.22.168?
I am trying to explore the possibility using NAT and/or outbound policy and even firewall???