On a related note, I'm in the process of setting up mail for our new domain, and Office365 was one of the options. I was surprised to see that Office 365 hosted domains have only one MX, which resolves to only two IPv4 addresses:
visser@cajones:~$ host geant-org.mail.protection.outlook.com. geant-org.mail.protection.outlook.com has address 213.199.154.87 geant-org.mail.protection.outlook.com has address 213.199.154.23 Both sit in the same network, which seems like a bad idea. Unless this is anycast? Can't tell from here. However, MS seems to have changed things recently: http://blogs.msdn.com/b/tzink/archive/2014/10/28/support-for-anonymous-inbound-email-over-ipv6-in-office-365.aspx Better late than never. The alternative for e-mail is Google Apps, which has IPv6 for years. Dick On 27 November 2014 at 03:00, Frank Bulk <frnk...@iname.com> wrote: > This afternoon I saw several log messages in our email server's logs in > relation to emails our local business customer (who uses our ISP email > server) was trying to send to a Microsoft Office 365 hosted domain: > > "[::ffff:12.43.166.xx] Site <target domain redacted> > (2a01:111:f400:7c0c::11) said after data sent: 554 5.7.1 Service > unavailable, message sent over IPv6 [2607:fe28:0:4000::10] must pass SPF or > DKIM validation (message not signed)" > > The PTR for 2a01:111:f400:7c0c::11 is > mail-by26c0c.inbound.protection.outlook.com. > > But when I check the MX record of the target domain I see there's no AAAA > for the <redacted>.mail.eo.outlook.com, just three A's. > > Fortunately we control our local business customer's DNS and I've added in > our email server's DKIM so that future emails, if they were sent over IPv6, > should be accepted by Microsoft. Our customer has no SPF record. > > > I also saw two log messages for two Microsoft Office 365 hosted domains: > 26 13:30:59.00 [56882563] Failed ::ffff:199.120.69.25 > <notification+kyg2k...@facebookmail.com> <target domain1 email redacted> > 9259 <1502549920004098-1497189607206...@groups.facebook.com> > "[::ffff:199.120.69.25] ubad=0, Site (target domain1 > redacted/2a01:111:f400:7c10::1:10) said: 550 5.2.1 Service Unavailable, > [target domain1 redacted] does not accept email over IPv6" > 26 19:04:52.00 [83985160] Failed ::ffff:12.43.166.20 <from redacted> <target > domain2 email redacted> 6546 <0EBCBB96763E41B2A4CD9A4CD3DD94BE@sp.local> > "[::ffff:12.43.166.20] ubad=1, Site (target domain2 email > redacted/2a01:111:f400:7c0c::11) said: 550 5.2.1 Service Unavailable, > [target domain2 email redacted] does not accept email over IPv6" > > There's no PTR for 2a01:111:f400:7c10::1:10. I checked the last 7 days of > logs I only saw these today. > > It's like Microsoft published some AAAA's for some MX records, but then > withdrew them, but not before there were a few failures. > > Frank > > > -- Dick Visser Sr. System & Networking Engineer GÉANT Association, Amsterdam Office (formerly TERENA) Singel 468D, 1017 AW Amsterdam, the Netherlands Tel: +31 (0) 20 530 4488 GÉANT Association Networking. Services. People. Learn more at: http://www.géant.org