On Wed, 14 Feb 2024 18:25:03 -0800 Stephen Satchell <l...@satchell.net> wrote:
> On 2/14/24 4:23 PM, Tom Samplonius wrote: > > The best option is what is happening right now: you can’t get new IPv4 > > addresses, so you have to either buy them, or use IPv6. The free market > > is solving the problem right now. Another solution isn’t needed. > > Really? How many mail servers are up on IPv6? How many legacy mail > clients can handle IPv6? How many MTA software packages can handle IPv6 > today "right out of the box" without specific configuration? Mine have been dual stack for a while (6 years? 8 years? don't exactly recall). However, I remember being enough of an early v6 adopter that it was a bit of a challenge to get IPv6 glue records set up for our DNS servers (that was long before I was brave enough to have my email servers on v6, though). > Does any IPv6 enabled ISP provide PTR records for mail servers? We do, of course, I can't speak for others. We also sub-delegate on request. However, we are small/local and cater to small businesses. > How does Google handle mail from an IPv6 server? I remember Google being where some of my first v6 email was coming from and going to. I would advise that if you allow your MTA to attach to all IPv6 addresses that you make sure all of them have REV PTR. Google, at least last time I looked, would deny email via IPv6 based solely on REV PTR errors. They are more forgiving over v4, but I suspect that has/had to do with more mature spam filtering considerations on v4 than v6. I once made the mistake of not having one of my secondary addresses set up with a REV PTR and Google rejected any email that came from that IP. --TimH