How to Restrict Sender or Entire Domain From Sending emails in Office 365

Hi Everyone this is Prem, I have worked as Microsoft 365 support ambassador for quite sometime, In this blog we will get to know How to Restrict Sender or Entire Domain From Sending emails in Office 365.

We can restrict senders from sending emails to users in our Office 365 environment by blocking them in the Anti spam filter policy.

Earlier the setting to block sender or domain was in Old Exchange Admin Center but now it has been moved to Security Admin center.

Steps to Restrict Sender or Entire Domain From Sending emails in Office 365:

Go to Security Admin Center and click on Policies and rules tab > Threat policy > Anti spam policies.

Alternatively you can directly go to the page by clicking on the link: https://security.microsoft.com/antispam and sign in with the admin account.

Click on Anti spam Inbound policy(Default) and scroll to the bottom of the page:

Under Allowed and blocked senders and domains click on Edit allowed and blocked senders and domains.

Here you will get the option to Allow or block the Sender or entire Domain:

You can click on the respective option here, I will block a sender from sending emails to users inside my organization so I will click on Manage sender under Blocked section.

Then Click on the +Add senders Option:

Type the sender email address to block and hit enter and then click on Add sender button:

The added sender should appear in the list, then click on Done and then Save:

You can follow the same to add domains as well in allow or block list in Office 365.

By default the emails sent by blocked sender and domain, gets marked as spam and delivers in the users Junk email folder.

Note:

If you add a domain in the Blocked domain list all the senders on that external domain will be Blocked.

Date: 01/03/2023

Author: Prem

Tag: How to Restrict Sender or Entire Domain From Sending emails in Office 365