When your Privia server sends notification, it sends them on behalf of the originator of the notification.  This can trigger anti-spoofing or fraud-detection filters in Outlook 365.  

To prevent the fraud detection flag, follow these steps (this must be done by an Outlook 365 administrator):

1. Identify the IP address of your Privia server (either through nslookup or by checking the header in a message from the server)
2. Sign into Exchange admin center (https://outlook.office365.com/ecp) with your Office 365 admin account.
3. Click Mail Flow
   1. Click +
   2. Choose Create a new rule…
   3. Click More options (Text link at bottom of the form).
4. Give the rule a name like "Sender is Privia Server"
5. Use the pulldown under *Apply this rule if...
   1. Select The sender...
   2. Select IP address is in any of these ranges or exactly matches
   3. Enter the IP address of your Privia Server
      1. click the "+"
      2. click "OK"
6. Use the pulldown under *Do the following...
   1. Select Modify the message properties
   2. Select set the spam confidence level (SCL)
   3. Select bypass spam filtering
7. Click Save