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Microsoft Office 365 Exposing User’s IP Address in Emails

Microsoft Office 365 Webmail exposes user's IP address in emails.




Microsoft Office 365's webmail interface has been accused for exposing the user's IP address injected into the message as an extra mail header.

This news comes as a rather major warning to those who resorted to Office 365 webmail interface to hide their IP address, because in reality they are not concealing anything.

The service injects an extra mail header into the email called x-originating-IP that contains the IP address of the connecting client, which for this situation is the user's local IP address and this all happens when an email is sent via Office 365 (https://outlook.office365.com/).

BleepingComputer even came around to test the webmail interfaces for Gmail, Yippee, AOL, Outlook.com (https://outlook.live.com), and Office 365.

As for Microsoft, it has removed the x-originating-IP header field in 2013 from Hotmail to offer their users much better security and privacy.

"Please be informed that Microsoft has opted to mask the X-Originating IP address. This is a planned change on the part of Microsoft in order to secure the well-being and safety of our customers."

However for Office 365, who 'caters to the enterprise', this header was deliberately left in so that admins could scan for email that has been sent to their respective organization from a specific IP address. This was particularly helpful for finding the location of a sender in the event of an account getting hacked.

And for Office 365 admins who don't wish to keep utilizing this header, they are allowed to make another new rule in the Exchange admin center that easily removes the header.



In any case, for security and auditing purposes, it is most likely a more shrewd decision to keep it enabled.

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