Here you have the ability to set up a mail server for the domain. You can set up more than one server and set the priority level of the server. More detail on doing this will be provided below.
You can define your mail server(s) in the Mail Server field. Only one server can be defined at a time. However, you can have more than one mail server per domain with different levels of priority. This provides failover. If a particular mail server is unavailable, DNS will automatically instruct it to use a different mail server.
The order in which the next server is chosen is known as the priority. The lower number the priority, the higher the precedence. In other words, a mail server configured with a priority of 10 will receive mail before one with a priority of 20.
You must complete the Mail Server and Priority fields. Once you are done, click the Create button and the server you just entered in will be displayed at the bottom.