The Reg does 240/4

Thu Feb 15 03:49:13 UTC 2024

> On 15 Feb 2024, at 13:25, Stephen Satchell <list at 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?

Lots.

>  How many legacy mail clients can handle IPv6?

Most.  If you are using mbox format there is no change.  The only ones that
don’t handle it are ones that don’t have support for creating IPv6 connections.

>  How many MTA software packages can handle IPv6 today "right out of the box" without specific configuration?

Most.  Really its been 20+ years since IPv6 was added to most of the mail
products that actually use TCP to connect to a mail store or to send email.

Just about the only thing that was needed to be done was to look for AAAA
records in addition to A records after looking up the MX records or to
replace gethostbyname with getnodebyname and then getaddrinfo.  This was a
10 minute job for most developers.

If you publish AAAA records for a service they will be used.

> Does any IPv6 enabled ISP provide PTR records for mail servers?

If they want to send email from those addresses they do.  

> How does Google handle mail from an IPv6 server?

Mostly the same as from IPv4.

> The Internet is not just the Web.

It isn’t.  But you could answer most of these by just looking at the email headers in
your own incoming mail.  Email has been delivered over IPv6 for over 2 decades now.

-- 
Mark Andrews, ISC
1 Seymour St., Dundas Valley, NSW 2117, Australia
PHONE: +61 2 9871 4742              INTERNET: marka at isc.org