[dwmtractor]

Here is the example file db.mydomain.com from the Hardy Heron install guide. Note the line I've colored in red:

;
; BIND data file for mydomain.com
;
$TTL    604800
@       IN      SOA     mail.mydomain.com. admin.mydomain.com. (
                         070725         ; Serial
                         604800         ; Refresh
                          86400         ; Retry
                        2419200         ; Expire
                         604800 )       ; Negative Cache TTL
;
@       IN      NS      mail
        IN      MX      10 mail
        IN      A       xxx.xxx.xxx.xxx
mail    IN      A       xxx.xxx.xxx.xxx