How to: Enable sending mail with IPv6 addresses

The dns_ip6_lookup feature is disabled by default as of InterWorx Version 5.1.7.  This means mail will not try to deliver via IPv6, unless manually configured. To enable sending over IPv6, first create a file called /var/qmail/control/dns_ip6_lookup with "1" as the contents:

echo 1 > /var/qmail/control/dns_ip6_lookup

[root@interworxtestbox home]# cat /var/qmail/control/dns_ip6_lookup
1
[root@interworxtestbox home]#

Then, create a file called /var/qmail/control/senderip6, with contents following this format: domain: ip6 address. Example:

[root@interworxtestbox home]# cat /var/qmail/control/senderip6
iwtest.net:2001:db8:0:1:1:1:1:1
[root@interworxtestbox home]#