[mailop] IPv6 addresses for Microsoft Office 365 hosted domains?

Brandon Long blong at google.com
Wed Dec 17 06:19:51 CET 2014


pretty sure we require one of dkim/spf/ptr, but not having dkim/spf, we'll
just look at it pretty harshly for spam.

Brandon

On Tue, Dec 16, 2014 at 1:03 AM, Bernhard Schmidt <Bernhard.Schmidt at lrz.de>
wrote:

> Hi Frank,
> >
> > Thanks for sharing your experience.  You may have been able to send
> > email to Google for some days from your IPv6 host without a PTR, but
> > I think that would only go on for a short time.  Have you tried
> > sending to Comcast?
>
> Note that I specifically do not suggest sending without PTR. We reject
> on missing FCrDNS even in IPv4 and are pretty happy with that (with an
> easy process to whitelist though). But I tried it to O365 and the mail
> went through nevertheless.
>
> According to
>
> https://www.m3aawg.org/sites/maawg/files/news/M3AAWG_Inbound_IPv6_Policy_Issues-2014-09.pdf
> which Google, Microsoft and LinkedIn claim to follow you need a "PTR and
> (SPF or DKIM)". And we've been preferring IPv6 outbound for 5+ years
> now, without any issues. 99% of our mail does neither have DKIM nor SPF.
>
> > From an ISP perspective, adding in an SPF (or equivalent TXT) record
> > for the IPv6 space of your ISP mail server would not be a hard thing
> > to do.  While not all email servers support DKIM, all DNS servers
> > support TXT records.
>
> Both SPF and DKIM are controlled by the sender domain, not by the
> operator of the sending mailserver. Think the classic Permit-by-IP
> smarthost run by ISPs, you just cannot make any assumptions there about
> the sender.
>
> Bernhard
>
>
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