Forum Discussion
HOW TO STOP BACKSCATTER?
Hi,
We use Office 365. One user suddenly got a few thousands NRD from Office 365 that he didn't send. I guess it's someone spoofed his email address and send emails and caused the backscatter. ...
Is the user on-premises and you relay the email through EOP? If so, enable backscatter protection in the anti-spam settings for your on-premises mailboxes.
If the user is a cloud mailbox in Exchange Online, ensure that the MX points to EOP and not on-premises and that backscatter protection is NOT enabled.
https://blogs.msdn.microsoft.com/tzink/2014/11/22/improving-backscatter-detection-with-boomerang/
Brian