You can verify it via commands
dig www.ostreff.info AAAA traceroute6 www.ostreff.info curl -6 www.ostreff.info
IPv6 Certification Badge for jostreff   It’s funny to see that in ipv6 worlds my site is 6 hop away. In ipv4 it’s 7 hops away.  
Jordan-Ostreffs-MBP:~ jostreff$ traceroute6 www.ostreff.info traceroute6 to jsp.ostreff.info (2001:470:1f0a:1830::2) from 2001:470:1f15:1303:31ca:10e:17ec:fdd8, 64 hops max, 12 byte packets 1 2001:470:1f15:1303:ba8d:12ff:fe5b:1ff0 1.168 ms 1.502 ms 0.762 ms 2 jostreff-1.tunnel.tserv11.ams1.ipv6.he.net 37.673 ms 36.499 ms 36.333 ms 3 10ge11-20.core1.ams1.he.net 35.521 ms 33.730 ms 51.334 ms 4 100ge5-1.core1.fra1.he.net 44.787 ms 37.329 ms 41.756 ms 5 tserv1.fra1.he.net 42.740 ms 42.329 ms 43.809 ms 6 jostreff-2-pt.tunnel.tserv6.fra1.ipv6.he.net 75.220 ms 72.095 ms 72.247 ms Jordan-Ostreffs-MBP:~ jostreff$ traceroute www.ostreff.info traceroute to jsp.ostreff.info (84.54.160.14), 64 hops max, 52 byte packets 1 10.0.1.1 (10.0.1.1) 1.455 ms 0.874 ms 0.847 ms 2 82-137-110-2.ip.btc-net.bg (82.137.110.2) 2.043 ms 1.629 ms 1.429 ms 3 83-228-105-49.ip.btc-net.bg (83.228.105.49) 7.621 ms 8.028 ms 7.951 ms 4 83-228-105-50.ip.btc-net.bg (83.228.105.50) 13.347 ms 11.934 ms 10.202 ms 5 * * * 6 classic.classic-bg.net (84.54.160.14) 13.115 ms 9.090 ms 8.943 ms 7 classic.classic-bg.net (84.54.160.14) 9.356 ms 9.351 ms 9.125 ms
Next task to build dualstack tcp46 mail system. Already passed also ipv6 enabled mail system.