Setting the Mail Exchanger (MX) preference is done through a special syntax in the host name entry field.
Where MX Preference is the preference you wish to use and <hostname> is the hostname that will be associated with MX record.
For example the following configuration
would create the following MX and corresponding A RR's
$ORIGIN example.com. mail1 30 IN A 192.168.1.226 30 IN MX 10 mail1.example.com. mail2 30 IN A 192.168.1.227 30 IN MX 20 mail2.example.com.
Keep in mind that MX preference only has significance in relation to other MX records in the same domain. This means that mail1 with a preference of 10 will be selected first and mail2 with a preference of 20 used in the event that mail1 is unreachable. Also keep in mind that changing the preferences to 100 and 200 respectively would give the exact same results.
Currently the Ecessa device does not support a preference of 0. Using 0 as the MX preference value will result in the default MX for that configuration section. Simple host records start at 500 incrementing by 1 for each subsequent MX entry. Load Balanced records default to 10 also incrementing for each subsequent MX record in that section.