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RNalivaika's avatar
RNalivaika
Iron Contributor
May 04, 2020

Exchange Online Protection SPF record

Hi, I have received a message sent via Exchange Online host IPv6 "2603:10a6:20b:c0::31". The message was marked as spam because of SPF fail. Subnet "2603:10a6:20b:c0::/64" is not in the list of O365 ...
exchange online
office 365
jabberwockdb123's avatar
jabberwockdb123
Copper Contributor
Oct 07, 2022
I used "v=spf1 ip6:2603:10b6::/37 include:secureserver.net ~all". I believe it includes most IP's starting with 2603:10b6 which overcompensates. But I couldn't think of any other way. Most of the emails pass through with this, but I still see some IP's which are not designated... For example 2603:10b6:a03:202::9 is not designated.
Another odd thing is when I receive an email via Gmail, even if the email passes SPF, Gmail sometimes flags it as possible spam.
AdamS550's avatar
AdamS550
Copper Contributor
Dec 04, 2023

we had the same issue all of sudden most of our emails was marked spam and when we contacted MS support they fallow the standard MS support spam filter, email policies ..etc even though we clearly told them it seems the emails that was send from IPV6 like 2603:10c6:10:e::17 it was marked as spam and this IP is belong MS. why is that? after 3 days of none sense and lost of emails we did our investigation 

https://www.spf-record.com/spf-lookup/spf.protection.outlook.com?ip=2603:10c6:10:e::17

IPV6 start with 2603: is not part of spf recorders that cause our email to fails SPF check further more the entire 2603:1000::/24 is belong to Microsoft network.

since we added the ipv6 record to our spf record our email seems to be fine 

v=spf1 include:spf.protection.outlook.com ip6:2603:1000::/24 -all

until MS figure out how to implement basic things like SPF 🙂 

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