Hi, thank you very much for your post. You were absolutely right about the bind configuration file needing what you posted.
I think partly the problem I've had understanding this is the DNS record with the company that hosts the domain name, is a bit confusing. The only entries you can enter are an A record and an MX record for the domain zapgun.net .
Imajr.com Free Online Image Community
With the interface you can't put names in without it converting it to a numbered IP address.
It seems to me that this makes an MX record for zapgun.net that points to mailserver.zapgun.net which has the same IP address.
Can anyone tell me if this is correct?
Any help is gratefully appreciated (and hopefully other people that use the forums can get some better ideas about DNS records needed for Zimbra).