Tom, The solution is easy, just have a dual-stack MX record. $ host gmail-smtp-in.l.google.com. gmail-smtp-in.l.google.com has address 172.253.115.26 gmail-smtp-in.l.google.com has IPv6 address 2607:f8b0:4004:c06::1a Servers using IPv6 connect to IPv6 as needed. Matthew On 2/14/2024 9:26 PM, John Levine wrote:

It appears that Stephen Satchell<list@satchell.net> said:

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On 2/14/24 4:23 PM, Tom Samplonius wrote:

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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 tod