why IPv6 isn't ready for prime time, SMTP edition

Laszlo Hanyecz laszlo at heliacal.net
Tue Mar 25 23:07:16 UTC 2014


The OP doesn't have control over the reverse DNS on the AT&T 6rd.  Spam crusades aside, it can be seen as just another case of 'putting people in their place', reinforcing that your end user connection is lesser and doesn't entitle to you to participate in the internet with the big boys.  How does one dare run a 'server' without being a member of a RIR?

One would hope that with IPv6 this would change, but the attitude of looking down on end subscribers has been around forever.  As seen in the other thread being discussed here, people are already looking for ways to block end users from participating.  

-Laszlo


On Mar 25, 2014, at 10:38 PM, Rich Kulawiec <rsk at gsp.org> wrote:

> On Tue, Mar 25, 2014 at 02:57:15PM -0600, Brielle Bruns wrote:
>> Nothing wrong with my mail server setup, except the lack of RDNS.
>> Lacking reverse should be one of many things to consider with
>> rejecting e-mails, but should not be the only condition.
> 
> Lack of rDNS means either (a) there is something temporarily wrong with
> rDNS/DNS or (b) it's a spam source or (c) someone doesn't know how to set
> up rDNS/DNS for a mail server.  Over the past decade, (b) has been the
> answer to about five or six 9's (depending on how I crunch the numbers),
> so deferring on that alone is not only sensible, but quite clearly a
> best practice.  If it turns out that it looks like (b) but is actually
> (a), then as long as the DNS issue clears up before SMTP retries stop,
> mail is merely delayed, not rejected.  And although *sometimes* it's
> (c), why would I want to accept mail from a server run by people who
> don't grasp basic email server operation best practices?   (Doubly so
> since long experience strongly suggests people that botch this will very
> likely botch other things as well, some of which can result in negative
> outcomes *for me* if I accomodate them.)
> 
> Of all the things that we need to do in order to make our mail servers
> play nice with the rest of the world, DNS/rDNS (and HELO) are among
> the simplest and easiest.
> 
> ---rsk
> 
> p.s. I also reject on mismatched and generic rDNS.  Real mail servers have
> real names, so if [generic] you insist on making yours look like a bot,
> I'll believe you and treat it like one.
> 




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