Office 365 Exchange IP range

[Oliver McErlane]

Hi,

When I try and share and email a document with fellow staff members, I get the following error, see screenshot.

Our on premise server treats them as spoofed emails.

What is the list of ip ranges that we need to allow?

Nb. The emails that are blocked are the ones coming from my email address. We are still using on premise Exchange. Emails coming from no-reply@sharepointonline.com are ok.

thanks,

Ollie

[#2]

The actual DNS code/message is not visible, so we can only guess here. But if they are indeed blocked as spoof attempts, you should check why exactly your On-Prem appliance is treating them as such.

Just FYI, a year ago a change was made on O365 side specifically to prevent such situations. Those notifications are now sent via EWS, impersonating the user, as detailed here: https://support.microsoft.com/en-us/help/3134824/information-about-changes-to-the-address-that-is-us...