Score:0

Can we determine from email headers that these two IP6 addresses came from the same person?

cc flag
EDO

I'm trying to determine whether the emails came from the same office or person, but lack the in-depth knowledge of IP6 and understanding of the meaning of the same "subnet prefix".

From the email header, the IP6 from:

Sender A: 2a01:111:f403:7005::72f
Sender B: 2a01:111:f403:7005::609

What can we conclude with certainty from the senders? What can be assumed beyond reasonable doubt?

diffchecker results on email headers

Score:3
za flag

Not that easy.

The two IP's belong to the same 2a01:111:f403:7005::0/64, which we could normally associate with a single office/connection.

But in this case the main subnet class is 2a01:110::/31, registered by Microsoft; so these IPs are not the users' addresses, but from Microsoft Otulook 365 servers. You can see it in the email headers as they resolve to ***.outbound-protection.outlook.com.

In this case you can't get sender IP address as it is masked by Outlook Online.

EDO avatar
cc flag
EDO
I understand, thank you for your explanation!
mangohost

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