> On Wed, Jul 02, 2008 at 10:47:53PM -0700, 'kent' wrote:
> [..]
> > However, this last address, 2001:470:1:76:2c0:9fff:fe3e:4009, is not
> > explicitly configured on the sending server; instead, it is being impli=
> citly
> > configured through ip6 autoconf stuff:
> 
> Which (autoconfig) you should either not be using on servers, or you=20
> should be configuring your software properly to select the correct=20
> outbound address. (I prefer to use the autoconfig one for 'management'=20
> and using a 'service address' for the service).

        And what is someone who doesn't have a permanent box with
        a static address to do that wants to use TLS to verify
        that one is actually talking to the remote party you are
        expecting to?

        A mobile machine can register its current addresses in the
        DNS regardless much more easily than it can register its
        reverse PTR records.

        Use the ISP's servers?  I don't trust the ISP's servers to do
        the right job.  I don't trust that there is not a copy of the
        correspondence being made and being sent somewhere else.  I
        have NO idea if they are setup to use TLS or not outbound

        Lack of PTR should NEVER be the SOLE reason for rejecting
        email.  I have not problem with is being a weighting into
        the decision of whether a piece of email is spam or not.
        Just don't make it map to 100%.

> SMTP shows that it is perfectly usable for these situations as it nicely =
> 
> rejects the message with a proper message automatically telling you on=20
> how to solve it.
> 
> > That is to say, it appears the ietf.org mail server is probably now rej=
> ecting
> > mail from *any* box that is getting a default global ipv6 address, sinc=
> e
> > those addresses will most likely not be in ip6.arpa.  There may be a wh=
> ole
> > lot of boxes in this situation.=20
> 
> Those boxes are not set up correctly thus should not be sending email in =
> 
> the first place.

        A PTR is not a requirement for sending email.  The IETF
        should live by it's own dog food and accept email from sites
        without PTR records.
 
> For that matter you should actually be=20
> firewalling+logging port 25 outbound so you can monitor any host in your =
> network doing illegal SMTP connects. Spam bots don't use IPv6 yet=20
> (afaik), but when they are aware how 'open' everything is and especially =
> that RBL's don't exist yadda yadda, they might just switch over to that.
> Good that the mainstream spamreceivers (gmail/yahoo/etc) don't have IPv6 =
> 
> yet as that would change that scenario.
> 
> Configure your mailservers correctly, it helps you send out mail, and it =
> 
> helps avoid others receiving crap from you.

        If you want to demand PTR records then you need to make it
        a requirement of address allocations that control of the
        reverse DNS entry passes down to the actual user of the
        addresses. 

        Mark

> Greets,
>   Jeroen
> 
> --
> 
> For postfix folks:
> http://www.postfix.org/IPV6_README.html
> 8<--------------------------------------------------------
> /etc/postfix/main.cf:
>      smtp_bind_address6 =3D 2001:240:587:0:250:56ff:fe89:1
> -------------------------------------------------------->8
> Other SMTP servers have similar mechanisms.
-- 
Mark Andrews, ISC
1 Seymour St., Dundas Valley, NSW 2117, Australia
PHONE: +61 2 9871 4742                 INTERNET: [EMAIL PROTECTED]
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