Fully qualified domain name (FQDN)
The FQDN page of the Configuration Wizard is used to specify the appliance fully qualified domain name (FQDN), as configured in your public DNS. This setting is used for the HELO/EHLO connection and is critical for proper email security software operation. An incorrect fully qualified domain name may cause disruptions in email traffic flow.
Enter the appliance FQDN in the field Fully Qualified Domain Name
FQDN format is mail.parentdomain.com.
This FQDN appears as the default entry on the page .