Send & Receive Issues

How to Remove a Microsoft 365 Mailbox from Restricted Users

Maira Mehtab Sep 27, 2026 870 views

Question details

The user needs to restore outbound email sending capabilities for an email address that was marked as spam or restricted while using automation tools like HubSpot.

Product: Microsoft 365 Mail
Device & OS: not provided
Scenario: An email account used for automated campaigns or bulk sending triggered Microsoft's spam filters and is now blocked from sending outbound messages.
Observed behavior: The mailbox has been placed on the Restricted Users list, resulting in all outbound emails failing to send or bouncing back.

Before you start

Ensure you have global administrator or security administrator privileges in your Microsoft 365 tenant, as standard users cannot access the Defender portal to unblock accounts.

Solution 1Recommended

Remove Restriction via Microsoft 365 Defender Portal

Use the Defender portal as an administrator to unblock a business mailbox that was restricted for sending spam.

This method applies to Microsoft 365 business and enterprise accounts. When Microsoft's threat policies detect suspicious outbound activity, it locks down the mailbox to protect the domain's reputation. Only an admin can review and lift this block.

Log into the Defender Portal

Navigate to the Microsoft 365 Defender portal at security.microsoft.com and sign in with your global administrator credentials.

Locate Restricted Entities

In the left-hand navigation menu, go to Email & collaboration, then click on Review, and select Restricted entities (or Restricted users).

Unblock the Account

Find the blocked email address in the list, click on it to open the details pane, and select the 'Unblock' action. Follow the prompts to confirm the removal.

Wait for Propagation: It can take up to 24 hours for the restrictions to be fully lifted across Microsoft's servers and for outbound email sending to resume normally.

Solution 2

Recover a Personal Microsoft Account

Follow account recovery steps if a personal Microsoft email account (like Outlook.com) gets restricted.

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Frequently Asked Questions

Why did my Microsoft 365 mailbox get restricted while using HubSpot?

Microsoft 365 places strict limits on outbound email volume to prevent spam. When automation tools like HubSpot send too many emails in a short period, or if the emails trigger spam filters, Microsoft automatically restricts the mailbox to protect your domain's reputation.

How long does it take for the mailbox to be unblocked?

Once an administrator initiates the unblocking process in the Microsoft 365 Defender portal, it typically takes between 1 and 24 hours for the changes to sync and for the mailbox to fully regain sending privileges.

Can I remove myself from the Restricted Users list?

No, standard users do not have the permissions required to access the Restricted entities page in the Defender portal. You must contact your organization's IT admin or global administrator to resolve this issue.

How can I prevent my automated emails from being marked as spam in the future?

To avoid future restrictions, consider using dedicated bulk email services (like SendGrid or Mailchimp) for high-volume campaigns instead of standard Exchange mailboxes. Additionally, ensure your domain has properly configured SPF, DKIM, and DMARC records.

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