Utilities: Administration: Server: Server Settings: Network Settings: DNS
ListManager includes its own DNS resolver, and does not require another. We STRONGLY recommend that you use ListManager's DNS resolver. ListManager's DNS resolver has been optimized for fast email delivery. However, if you would like to use your own DNS server, you may specify its IP address here, and whether you would like to always use it, or only in the event ListManager's DNS resolver fails.
DNS Server IP Address
The IP address of the DNS server ListMa-ager should use. By default, this setting is blank, meaning ListManager uses its own DNS resolver.
Use Only for Fallback
This setting allows the DNS server specified above to be used only if the ListManager DNS resolver fails. Set to "yes" by default.
NOTE: To make changes in these settings take effect, you must restart ListManager.
More
1. Server Settings: Network Settings: Receive Email
2. Server Settings: Network Settings: Deliver Email
3. Server Settings: Network Settings: Relay Hosts
4. Server Settings: Network Settings: Ports
5. Server Settings: Network Settings: DNS