Glad to hear that Microsoft did this on their O365 platform.
Is there an RFC or other standard that we can point other email providers to about implementing email admission in this manner? Frank From: [email protected] [mailto:[email protected]] On Behalf Of Bill Owens Sent: Wednesday, April 22, 2015 8:08 AM To: [email protected] Subject: Re: Looking for a Microsoft person who can help w/ v6 and Office365 email On Wed, Apr 1, 2015 at 8:02 PM, Bill Owens <[email protected] <mailto:[email protected]> > wrote: > > We've been running our Office365 mail account for a few weeks now with IPv6 > enabled. We went into this knowing that Microsoft was going to enforce SPF > checks on inbound mail, and we've run into a number of issues with people > sending mail over v6 transport and having bad SPF records (or none). So far > we've been able to resolve all but one of those issues, or are in the process > of doing so; that's not a big deal. The one that won't fix their record is > going to require us to resubscribe to a few mail lists, not the end of the > world. > > However, we've discovered that there are sporadic failures even when there > are valid SPF records, and in some cases even when the email enters the > Microsoft 'world' using v4 and transitions to v6 between two Microsoft > servers - at which point the SPF check is applied even though the message was > "accepted" several hops prior, and the check sometimes fails. That's > something we can't fix on our own. > I don't know whether this is in response to the problems we've reported, but Microsoft has changed their attitude towards SPF and IPv6 just a little. Rather than returning a 5xx error code, which causes the mail to bounce immediately, they're going to return 4xx and allow the sender to attempt redelivery. This ought to prevent the majority of bounces that we've been seeing, although it doesn't fix the underlying issue(s) that cause the false SPF failures: http://blogs.msdn.com/b/tzink/archive/2015/04/18/office-365-will-slightly-modify-its-treatment-of-anonymous-inbound-email-over-ipv6.aspx Bill.
