How To Add Domain in Allow/Block List (Admin Access Only)

1. Login to portal.office.com using the admin credential.

2. Click on this link to go to Anti-Spam Policy page.

3. Under Anti-spam inbound policy (Default), scroll down until Allowed and blocked senders and domains section. 

Click on the Edit allowed and blocked senders and domains.

4. You may add the senders email address or the domains in the allow or blocked base on your requirement.