Suppose you have one domain (called ipswitch.net) and three servers. All three servers accept incoming mail on the same priority and all have a portion of the user database. You would make the following entries in your DNS:
DNS entries:
ipswitch.net
IN MX 10 mail1.ipswitch.net
IN MX 10 mail2.ipswitch.net
IN MX 10 mail3.ipswitch.net
Mail1 IN A 1.1.1.1
Mail2 IN A 2.2.2.2
Mail3 IN A 3.3.3.3
You create the following peer lists in the IMail Server software on the three servers:
Peer list on mail1:
Peer list on mail2:
Peer list on mail3:
In the hosts file on each of the three servers, make the three entries:
On each of the three machines, make sure the domain (for example, ipswitch.net) is the only entry in the Domain Aliases box on the Domain Properties page. This alias names the primary domain used to send and receive mail.
Important: The domain alias cannot be a primary domain associated with a particular host. Do not enter IP addresses in the Domain Aliases box.
Important: On each of the three computers, make sure that Default Host on the System > System Settings tab is empty when using peer lists.