Re: not delivering, and History of fallback to A
2008-03-30 09:59:01
This also ignores the issue of what is the right thing to do in the
transitional case where there's no MX record but a mixture of A and AAAA
records. Only falling back to the A record subset seems, well, wrong.
Well, gee, that's what happens right now. The question is where we go
from here.
[... that] doesn't seem like much of an argument compared to the
advantages laid out in my last message of having hosts default to not
being mail servers.
I assume you're referring to the problem of mail sitting in the queues waitinfg
to be delivered to a system that's never going to accept it. I'm afraid I don't
buy your reasoning on this one either.
10 years or so ago this used to be a real issue - we used to get customer
complaints all the time about stuck mail to some router, or to lab PCs, or
whatever.
The mail sitting in the queues isn't the problem, it's the load on all of
the hosts that the bogus mail is hammering on. Remember my non-mail host
with the 30,000 spams per day. Those aren't just attempts, by the way, I
set up an MTA and collect 30,000 actual spams. I tried soft failing and
the load was somewhat more.
The lack of complaints is probably because we no longer run versions of
sendmail that report back every two hours to say that your message hasn't
bounced yet. Most bounces these days are spam blowback, which tells me
that if the user doesn't see a failure report really soon while he still
remembers sending the message, it'll be lost in the noise.
Speaking of lost in the noise, one thing that's really different from 25
years ago is that reliable mail depends as much on not delivering spam as
it depends on delivering the real mail. I don't know how many of the
other people in the conversation see the feedback reports when people at
AOL, Hotmail, and other large ISPs hit the spam button on your users'
mail, but if you can arrange to see them, do so, because it's a real eye
opener. A message that is hidden in a mailbox full of spam is lost as
thoroughly as one that was never delivered. I cannot tell you how many
spam reports I get for utterly unobjectionable mail that was clearly
scooped up with a hundred other messages and reported en masse. I've had
to tell people on my church's mailing list that no, I can't keep putting
you back on the list if you keep reporting it as spam. So with that in
mind, even if something makes it a little harder for the least competent
to set up their mail servers, that's OK if will tend to improve mail
reliability overall.
With respect to DNS setup, I spend a certain amount of time helping people
fix their SPF records. (Not because SPF is a good idea, but because it's
hard to get mail into Hotmail if you don't.) I see a fair number of DNS
management control panels, and I don't recall seeing any that made MXes
hard to set up. Maybe they exist, but I'd be surprised if they were any
more common than any other random DNS breakage.
R's,
John
PS:
So I believe the correct course going forward is to have the same fallback
rules for AAAA that we do for A. Having said all this, it certainly isn't a
showstopper for me if this goes the other way
I can live with the current ambiguous language, particularly if we agree
that we need to have some way to declare in the DNS that a name accepts no
mail, be it no default to AAAA, MX . or whatever.
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Re: not delivering, and History of fallback to A,
John R Levine <=
- Re: not delivering, and History of fallback to A, ned+ietf-smtp
- Re: not delivering, and History of fallback to A, John R Levine
- Re: not delivering, and History of fallback to A, ned+ietf-smtp
- Re: not delivering, and History of fallback to A, John R Levine
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Re: not delivering, and History of fallback to A, Dave Crocker
Re: not delivering, and History of fallback to A, Russ Allbery
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Re: not delivering, and History of fallback to A, Dave Crocker
Re: not delivering, and History of fallback to A, Keith Moore
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