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Remove blocked connectors from the Restricted entities page

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In Microsoft 365 organizations with mailboxes in Exchange Online or standalone Exchange Online Protection (EOP) organizations without Exchange Online mailboxes, several things happen if an inbound connector is detected as potentially compromised:

  • The connector is prevented from sending or relaying email.

  • The connector is added to the Restricted entities page in the Microsoft Defender portal.

    A restricted entity is a user account or a connector that's blocked from sending email due to indications of compromise, which typically includes exceeding message receiving and sending limits.

  • If the connector is used to send email, the message is returned in a non-delivery report (also known as an NDR or bounced message) with the error code 550;5.7.711 and the following text:

Your message couldn't be delivered. The most common reason for this is that your organization's email connector is suspected of sending spam or phish and it's no longer allowed to send email. Contact your email admin for assistance. Remote Server returned '550;5.7.711 Access denied, bad inbound connector. AS(2204).'

For more information about compromised connectors and how to regain control of them, see Respond to a compromised connector.

The procedures in this article explain how admins can remove connectors from the Restricted entities page in the Microsoft Defender portal or in Exchange Online PowerShell.

For more information about compromised user accounts and how to remove them from the Restricted entities page, see Remove blocked users from the Restricted entities page.

What do you need to know before you begin?

  • Open the Microsoft Defender portal at https://security.microsoft.com. To go directly to the Restricted entities page, use https://security.microsoft.com/restrictedentities.

  • To connect to Exchange Online PowerShell, see Connect to Exchange Online PowerShell.

  • You need to be assigned permissions before you can do the procedures in this article. You have the following options:

    • Microsoft Defender XDR Unified role based access control (RBAC) (If Email & collaboration > Defender for Office 365 permissions is Active. Affects the Defender portal only, not PowerShell): Authorization and settings/Security settings/Detection tuning (manage) or Authorization and settings/Security settings/Core security settings (read).

    • Exchange Online permissions:

      • Remove connectors from the Restricted entities page: Membership in the Organization Management or Security Administrator role groups.
      • Read-only access to the Restricted entities page: Membership in the Global Reader, Security Reader, or View-Only Organization Management role groups.

    • Microsoft Entra permissions: Membership in the Global Administrator*, Security Administrator, Global Reader, or Security Reader roles gives users the required permissions and permissions for other features in Microsoft 365.

      Important

      * Microsoft recommends that you use roles with the fewest permissions. Using lower permissioned accounts helps improve security for your organization. Global Administrator is a highly privileged role that should be limited to emergency scenarios when you can't use an existing role.

  • Before you follow the procedures in this article to remove a connector from the Restricted entities page, be sure to follow the required steps to regain control of the connector as described in Respond to a compromised connector.

Remove a connector from the Restricted entities page in the Microsoft Defender portal

  1. In the Microsoft Defender portal at https://security.microsoft.com, go to Email & collaboration > Review > Restricted entities. Or, to go directly to the Restricted entities page, use https://security.microsoft.com/restrictedentities.

  2. On the Restricted entities page, identify the connector to unblock. The Entity value is Connector.

    Select a column header to sort by that column.

    To change the list of entities from normal to compact spacing, select Change list spacing to compact or normal, and then select Compact list.

    Use the Search box and a corresponding value to find specific connectors.

  3. Select the connector to unblock by selecting the check box for the entity, and then selecting the Unblock action that appears on the page.

  4. In the Unblock entity flyout that opens, read the details about the restricted connector. You should go through the recommendations to ensure you're taking the proper actions in case the connector is compromised.

    When you're finished in the Unblock entity flyout, select Unblock.

    Note

    It might take up to 1 hour for all restrictions to be removed from the connector.

Verify the alert settings for restricted connectors

The default alert policy named Suspicious connector activity automatically notifies admins when connectors are blocked from relaying email. For more information about alert policies, see Alert policies in the Microsoft Defender portal.

Important

For alerts to work, audit logging must be turned on (it's on by default). To verify that audit logging is turned on or to turn it on, see Turn auditing on or off.

  1. In the Microsoft Defender portal at https://security.microsoft.com, go to Email & collaboration > Policies & rules > Alert policy. Or, to go directly to the Alert policy page, use https://security.microsoft.com/alertpoliciesv2.

  2. On the Alert policy page, find the alert named Suspicious connector activity. You can sort the alerts by name, or use the Search box to find the alert.

    Select the Suspicious connector activity alert by clicking anywhere in the row other than the check box next to the name.

  3. In the Suspicious connector activity flyout that opens, verify or configure the following settings:

    • Status: Verify the alert is turned on .

    • Expand the Set your recipients section and verify the Recipients and Daily notification limit values.

      To change the values, select Edit recipient settings in the section or select Edit policy at the top of the flyout.

      • On the Decide if you want to notify people when this alert is triggered page of the wizard that opens, verify or change the following settings:

        • Verify Opt-in for email notifications is selected.
        • Email recipients: The default value is TenantAdmins (Global Administrator members). To add more recipients, click in the empty area of the box. A list of recipients appears, and you can start typing a name to filter and select a recipient. Remove an existing recipient from the box by selecting next to their name.
        • Daily notification limit: The default value is No limit.

        When you're finished on the Decide if you want to notify people when this alert is triggered page, select Next.

      • On the Review your settings page, select Submit, and then select Done.

  4. Back in the Suspicious connector activity flyout, select at the top of the flyout.

Use Exchange Online PowerShell to view and remove connectors from the Restricted entities page

To view the list of connectors that are restricted from sending email, run the following command in Exchange Online PowerShell:

Get-BlockedConnector

To view details about a specific blocked connector, replace <ConnectorID> with the GUID value of the connector, and then run the following command:

Get-BlockedConnector -ConnectorId <ConnectorID> | Format-List

For detailed syntax and parameter information, see Get-BlockedConnector.

To remove a connector from the Restricted entities list, replace <ConnectorID> with the GUID value of the connector, and then run the following command:

Remove-BlockedConnector -ConnectorId <ConnectorID>

For detailed syntax and parameter information, see Remove-BlockedConnector.

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