On 28 Sep 2020, at 11:38, Keith Moore <moore(_at_)network-heretics(_dot_)com>
wrote:
On 9/28/20 4:38 AM, Laura Atkins wrote:
Do you think if the wording in the RFC is changed that established behavior
will change? That the SMTP servers will be reconfigured to stop doing what
they are doing?
I think most operators will not bother to change their existing practices
if/when the RFC wording changes.
That’s what I thought.
But if the RFC recommends poor practice, it will be harder to change that
poor practice, because some people will say "but the RFC says...!" So the
RFC should not recommend poor practice.
What is your evidence that it is poor practice?
If, OTOH, the RFC recommends NOT filtering based on EHLO arguments, then it
will be at least a bit easier for operators to stop doing that when they
start seeing that it's a bad idea.
What is your evidence that it’s a bad idea?
I'm thinking long term here. I expect 5321bis, if we do our jobs right, to
be around for decades. So its recommendations need to make sense in the
long term rather than the short term.
That presumes that your recommendation makes sense and that allowing any random
NATed machine to connect to the internet and send mail is a good thing. I think
we have ample evidence that this is actually an abuse vector and a bad thing.
What changes do you see happening that will make this currently good practice
become a bad one.
It doesn't actually bother me that much if existing operators filter based on
EHLO validation as long as they re-evaluate that policy over time. I expect
operators to be pragmatists. But I really do expect use of NAT64 to
increase, and I really think it's unhelpful to network operators if reliable
email operation requires them all to maintain static IPv4 addresses and
connections to the public IPv4 Internet. It's silly for email to delay a
transition away from IPv4 for this reason.
Can you explain this use case in more detail?
laura
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