What is the Microsoft recommendation around IPv6 in the latest version of Exchange?
In the 2010 world, most of the Exchange admins went with the registry edits to disable IPv6 fully. With the release of 2013, Microsoft recommendation is not to disable IPv6 on the Exchange servers even if you are not using it. Exchange 2013 fully support IPv6 networks.
IPv6 support in 2013 requires IPv4 to be installed and enabled on all Exchange 2013 servers. Uninstalling IPv4 from your Exchange 2013 servers isn’t supported by Microsoft.
In short, no more registry edits on 2013 boxes and leave IPv6 enabled.