myCorp.com MX preference = 10, mail exchanger = 126.96.36.199
I have two public IPs.
My firewall map 188.8.131.52 to my internal mail server: 10.0.0.5
Issue#1: if wan1 is down, I can not receive external email;
Issue#2: if wan1 is down, I cannot send mail to external through wan2 either because some mail server do reverse DNS check and reject my mail server if it connects through wan2.
If I add a new MX recod as follows:
myCorp.com MX preference = 10, mail exchanger = 184.108.40.206
on my firewall, I also map 220.127.116.11 to my existing mail server 10.0.0.5.
My goal is just to be able to send and receive mails through either or both of wan1 and wan2.
Q#1. If wan1 (18.104.22.168) is down, will external mail servers automatically try to send it to 22.214.171.124? vice versa?
Q#2. If wan1 is down, can my mail server send it through wan2 without being rejected? vice versa?
Q#3. If wan1 is preferred over wan2 when both are available, can I set the preference for wan1 lower than for wan2?