Disable IPv6 for Docker / Discourse / Exim4
The server running https://community.coops.tech/ isn't configured for IPv6 so we have messages like this in the /var/log/exim4/mainlog
:
2017-05-04 08:11:59 1d6Bri-0004qu-K9 H=ASPMX.L.GOOGLE.com [2a00:1450:400c:c0b::1a] Network is unreachable
We should disable IPv6 for now to prevent these.