The article provides a list of the instances in which you can use IPv6 addresses.
Symantec Messaging Gateway
• Enable IPv6 for your Scanners and Control Center and add IPv6 addresses to one or both of your Ethernet interfaces.
• Add IPv6 addresses and address ranges for access to your Control Center.
• If you enable IPv6 for your Ethernet interfaces, you can add IPv6 addresses to your SMTP configuration.
• If you enable IPv6 for your Ethernet interfaces, you can use IPv6 addresses and address ranges for Internal Mail
Hosts.
• Use IPv6 addresses in your Good Senders lists and Bad Senders lists.
• Query IPv6 addresses when you perform reputation lookups.
• Create reports to return information on IPv6 addresses or a mix of IPv4 and IPv6 addresses.
• View message audit logs for your IPv6 addresses.