On 8 May 2020, at 15:06, Ralph Seichter wrote:
* Bill Cole:
Some have IPv6 connectivity and address space but no motivation to
make their mail systems use IPv6.
A case of what we call Public Servant Mikado (whoever moves first has
lost). ;-)
Yes.
Seriously, I think that if one can support IPv6, one should
do it. Good hosting services and ISPs already offer native IPv6, and
those that don't should be pressured by customer demand to get their
act
together.
Because I work in multiple unrelated environments, I see many sides of
this.
The boutique hosting/connectivity/services provider I work with (with 2
ASs, US & EU BGP presence, multiple IPv4 and IPv6 allocations) can
provide native IPv6 to customers. None ever has ever asked for it. The
main production mail hosting system has a /24 reserved for its use (and
mostly in use) and we've never had any technical reason to deploy IPv6
on it or customer demand. It's just not a thing with any pressure behind
it.
If one has a working IPv4-only mail system, adding IPv6 is pure work
for no discernible benefit.
Adding a static IPv6 address to a Linux host is a simple one-time
effort
that takes a couple of minutes. Then, tweak some Postfix settings like
inet_interfaces, inet_protocols and maybe smtp_bind_address6. Create a
DNS AAAA record, update the SPF record.
Sure, for a one-IP Postfix system that's pretty easy.
However, if one has a clustered mail system that isn't Postfix with
scores of domains, each with their own IP on each of multiple nodes,
that's non-trivial work. For what? There is at least one large mail
system operator (Google) which explicitly has stricter criteria for
accepting mail from IPv6 sources, so maybe you don't even want to
ever send on IPv6 anyway to avoid having to suit them today and a dozen
others with different criteria next week. Does anyone worth worrying
about only send or receive on IPv6? Not that I'm aware of. Are there
tools for spam control of IPv6 incoming mail that match the IPv4 tools?
No.
Overall, I estimate that getting a Postfix-based MX IPv6-ready should
take about 15 minutes, and I think it is time well spent.
I'm not sure that it is for all mail operators, but even if I stipulate
the point: it's not what I was talking about.
The OP asked if IPv6-ONLY was practical. My reason for saying that it is
not (yet) was grounded in the reality that not all mail systems are
one-machine, one-IP, and/or Postfix. It's easy for anyone with a
one-machine one-IP Postfix system and IPv6 connectivity and an assigned
/64 to be IPv6-READY with minimal effort. It isn't realistic to expect
that everyone you want to exchange mail with has those prerequisites
and/or has put out whatever effort their systems require to use IPv6 for
email.
--
Bill Cole
b...@scconsult.com or billc...@apache.org
(AKA @grumpybozo and many *@billmail.scconsult.com addresses)
Not For Hire (currently)
