I have an Exchange 2010 server that is visible under 2 MX records
mx1.acme.com with 2 different IP addreses from 2 different network providers. They both report as
mx.acme.com when someone is sending us an email and they both report as
mx.acme.com when we send email. But for now the 2nd MX (and ip address that is sending the email has actually different domain name, reverse dns then the one it's reporting when it connects to other servers.
The problem is I don't know which IP Address will be used to send email out so I was thinking to setup same
mx.acme.com record in DNS for both Ip addresses, and same Reverse DNS for both at both providers.
Will that work just fine or I'm missing something? I guess then I just have to add one MX record and not two as it would be meaningless to add 2nd.
Current setup looks more or less like this:
MX record: acme.com IN MX 5 mail1.acme.com A record: mail1.acme.com IN A 192.168.10.17 MX record: acme.com IN MX 10 mail2.acme.com A record: mail2.acme.com IN A 192.168.10.18
And I would like to change it to:
MX record: acme.com IN MX 5 mail.acme.com A record: mail.acme.com IN A 192.168.10.17 A record: mail.acme.com IN A 192.168.10.18
As it's the only way I think this will go. The problem I can see is if one Ip address is down and dns will be pointing the server to it no matter what then some mails will bounce off. And I guess for that round-robin to work i will need TTL 0 so DNS (at hosting has to allow that).