Create O365 Rule to Allow Only Email from Specific IP Addresses

Create O365 Rule to only allow email from smart host — go to exchange admin center

Here is how to tighten up email delivery so that only approved senders, like smarthosts, can send email to your Office 365 accounts

Microsoft Exchange servers had a provision to allow only email from specific IP addresses or domains, finding that in Office 365 is a little more difficult as we will have to create a Rule to enact this type of filtering

Here are the Steps to Setup Only Email From Specific IP Address

Create Microsoft Office 365 Email Block Rule — go to the classic exchange admin center

Login to Office 365 as ad admin
Go to Exchange Admin Center
Go to Classic Exchange admin center
Go to Mail Flow
Go to RULES and then ADD RULE
See the image for the rules settings
Set Settings to APPLY THIS RULE if the sender is located outside the organization
Do the Following- – Deliver the message to the hosted quarantine
Except if the senders IP is in the Range