I am planning to setup a Zimbra Server on a private NAT network to deliver mail and receive mail from the internet as well as the local LAN.
I have read and understand all of the Split DNS documents but think there might be an easier way for simple networks. Wanted to see if anyone else thought that this might work or if I will need to setup Split DNS.
My current network consists of a Windows Terminal Server 2003 (NON DOMAIN setup) and a few workstations. I do not run internal DNS but relay everything to the ISP DNS. My domainname.com is purchased through an external registrar and the mail.domainname.com as well as domain MX settings are setup with the registrar's DNS server.
server hostname = mail.domainname.local
smtp server hostname set in zimbra = mail.domainname.com
zimbra domain = domainname.com
If user email@example.com sends an email to firstname.lastname@example.org the server will do a DNS lookup for domainname.com with the ISP's DNS. It will see that my primary MX record is set to mail.domainname.com. It would then get the IP address of mail.domainname.com (which would return as a public IP) and since it could not reach that address the email would fail delivery.
Here is the question if I put an entry into my server /etc/hosts file of "internal ip = mail.domainname.com" then the server should get that address after it does the MX lookup and could then find itself and deliver the mail?