Relating to the option to allow domains their own outbound IP for email, (and their own inbound HELO smtp value): https://www.directadmin.com/features.php?id=1692 this feature will extend the /etc/virtual/domainips file, such that, if you have an owned main IP on the domain (which should already be added to the domainsips file, when enabled), this will first do a lookup of all linked IPs on that owned IP. If there are any linked IPs, that will be the 2nd list, and if there are 0 linked, it will read the domain's ip_list file for the 2nd list. Once a list is obtained, the main IP type is checked, and the list is search for the "other" type. Eg, if the main owned IP is an IPv4, the type of the 2nd IP to be searched for will be IPv6, and vice-versa: if the main is IPv6, the 2nd is IPv4. If a 2nd is found, then the /etc/virtual/domainips file will hold, for example: domain.com: 22.214.171.124; fe80:0:0:0:10c:18ff:fc1a:638a If you're using the lan_ip option, this feature will not have any effect, since the external IPs cannot be bound to.