I'm trying to set up a Windows Server 2012 and a Linux Server (CentOS 7) to act as backup mail servers for each other.
They each host different domains. So lets say the Linux server is the host of domain1.com and has an MX record of priority 0
I want to have the Windows server be the backup mail server so I may have another MX record of priority 10.
So domain2.com may be the opposite, so the Windows server is primary and the Linux server is backup.
What would I have to do to make this work?