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

Tue Mar 25 17:55:11 UTC 2014

On Tue, Mar 25, 2014 at 1:43 PM, Brielle Bruns <bruns at 2mbit.com> wrote:
> On 3/25/14, 11:23 AM, John Levine wrote:
>>
>> Large mail providers all agree that v6 senders need to follow good
>> mail discipline, but are far from agreeing what that means.  It
>> certainly means proper rDNS, but does it mean SPF?  DKIM on all the
>> mail?  TLS on the connections?  At this point, I don't know and
>> neither does anyone else.  Fortunately we have at least another decade
>> of full IPv4 mail connectivity to figure it out.
>
>
> So, what's everyone's feelings about a rather large provider who blocks IPv6
> e-mail that has no RDNS, even though the sending domain has SPF records
> allowing the block, and proper DKIM set up?
>
> *looks directly at Google*
>
> Nothing like poorly thought out policy to break a rather successful IPv6
> roll-out for multiple customers.

Just an anecdotal observation.... what G appears to be doing is
flagging emails, received over IPv6, that are below a certain size
threshold.  I have zero problems sending bulk emails (discussions
lists), over IPv6, to G end users, but I do see consistent problems
sending small mgmt alerts (i.e. monit/munin) over IPv6 to G.

-Jim P.