[gerdesj]

"Standards don't have any cosmic significance." - true but then I suspect you would get a right shitty on if your preferred IP stack didn't generally behave in the same way as mine and you lost comms with the world.

This discusses some consequences of avoiding standards: https://tools.ietf.org/id/draft-thomson-postel-was-wrong-03....

Of course your DNS server can return whatever you fancy in response to a request. If you want to return an MX record that looks like an IP address then go ahead. I think the old restriction on a hostname being greater than two chars and no leading int has gone away. If a MTA is happy with the result then fine.

However, anti-spam systems will frown on things like that and will probably tut a bit. ... and drop your mail on the floor. You can do what you like - you could call these records "Liberty MX" but I will still drop your mail because I can't be arsed to analyse your intent. You don't follow email standards - DROP!