Please follow the steps to whitelist using Office 355
As an administrator of Office 365, you can whitelist the IP address using the IP filter feature in EAC. For details, please try the steps below:
1. Find the IP address.
2. Access EAC via https://outlook.office365.com/ecp/.
3. Click 'protection' in the left panel, then click 'connection filter' in the top.
4. You can then edit the default filter rule and add the IP address in the whitelist.
For more details, please refer to: Configure the Connection Filter Policy.
Customer Services Team