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      Defender for Office 365 Email Domain Block

      This guide will show an administrator how to specify a domain or address that users will no longer be able to communicate with.

      Role Requirements

      Procedure Scope: Administrators

      Required Group Membership: Admin.Security

      Handbook Reference

      Package: TBD

      Domain: TBD

      Modifies: TBD

      O365 Email Domain Block                                   

      1. Navigate to the Tenant Allow/Block Lists – Microsoft Defender portal, select Block under the Domains/Addresses tab.
      2. In the following window you can specify either the entire domain or specific addresses associated with a domain (max limit of 20). Specify the timeframe as Never Expire and provide a reference point for fellow administration on why the block has been instated. Click Add.

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