Zimbra Collaboration Suite 7.0
Zimbra Collaboration Suite 7.0
Quick Start Installation Guide
Open Source Edition

Zimbra™ Collaboration Suite Single Server Installation - Open Source > Configure DNS

Configure DNS
In order to send and receive email, the Zimbra MTA must be configured in DNS with both A and MX records. For sending mail, the MTA uses DNS to resolve hostnames and email-routing information. To receive mail, the MX record must be configured correctly to route the message to the mail server.
During the installation process, ZCS checks to see if you have an MX record correctly configured. If it is not, an error is displayed suggesting that the domain name have an MX record configured in DNS.
You must configure a relay host if you do not enable DNS. After ZCS is installed, go to the Global Settings>MTA tab on the administration console and uncheck Enable DNS lookups. Enter the relay MTA address to use for external delivery.
Even if a relay host is configured, an MX record is still required if the ZCS server is going to receive email from the Internet.