Ok, I think you're a bit confused. What you need to do is to call your DNS host, if you're not hosting your own DNS, and tell them you want the proper A and MX records created for your Spamsnake.
Bind configuration on your end is very minimum and doesn't require anything more advanced beyond the guide.
If your Spamsnake is, lets say, mailcatch, then you would tell your DNS host to setup an A record for mailcatch and then setup an MX record point all mails to the public IP of the mailcatch box.
Hope this sheds some light on the issue for you.
Home of the SpamSnake