Inline Protection for Internal Emails (Office 365 Mail) - Manual Configuration Required

After selecting the Protect (Inline) Internal Traffic checkbox and saving the threat detection policy, a pop up appears stating that some manual configurations are required.

If that happens, follow these two steps:

  1. Add a Mail Flow rule named Avanan.
  2. Edit the Avanan DLP Outbound Connector and check the Retain internal Exchange email headers checkbox.

Only after completing these changes, Avanan protects the internal emails in Protect (inline) protection mode.