Mailu: open relay over IPv6

[gizocz]

When enabled IPv6 in Mailu configuration, it create an open relay over IPv6 (IPv4 is ok).

I know, there is a FAQ and a danger notice in the setup wizard: _"Docker currently does not expose the IPv6 ports properly"_. But there is no a (big red) security warning about the open relay.

Using docker-ipv6nat solve the issue. It's looks like related to #332 (for IPv4).

[kaiyou]

We could add a big warning in the setup tool indeed.

[micw]

Till 1.8 we should at least the warning (and probably description how to use docker-ipv6nat)
@gizocz A PR to the docs is highly appreciated

[muhlemmer]

Uhh, the setup has a red warning about + a link to the FAQ:

https://mailu.io/1.7/faq.html#how-to-make-ipv6-work

Put it there myself :innocent:, and running the setup since.

Edit: That's suggesting docker-ipv6nat as the OP mentioned.

[Nebukadneza]

Haha, nice one. Since @muhlemmer already did this a long time ago in #886 , and I believe this should be quite clear, I’m taking the liberty of closing this.