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 (Adding a New IMail Domain, Setting Domain Properties). 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 the Default Mail Domain or IP box on the Services > SMTP tab is empty when using peer lists.