Security Policy Errors

How to Restore Microsoft 365 Outbound Email After Spam Activity

John Wilson Oct 21, 2026 869 views

Question details

The user needs to unblock outbound email capabilities in Microsoft 365 after the system restricted sending due to detected spam or suspicious activity.

How to Restore Microsoft 365 Outbound Email After Spam Activity

Product: Microsoft 365
Device & OS: not provided
Scenario: An administrator needs to restore outbound email access for a restricted mailbox or an entire tenant blocked for spam activity.
Observed behavior: Users are unable to send outbound emails, and the account or tenant is flagged and restricted by Microsoft 365 security policies.

Before you start

Before unblocking the account, thoroughly investigate compromised credentials, malicious forwarding rules, unauthorized applications, and relay settings to prevent immediate re-restriction.

Solution 1Recommended

Unblock a Single Restricted Account via the Defender Portal

Use this method if only specific user accounts have been blocked from sending outbound emails by Microsoft 365.

Administrators can use the Restricted Users page in the Microsoft 365 Defender portal to remove the block from specific accounts. Once unblocked, it typically takes about one hour for the outbound email capability to be fully restored.

Navigate to the Restricted Users portal

Open your web browser and go to https://security.microsoft.com/restrictedusers. Sign in using your Microsoft 365 administrator credentials.

Select the affected account

Locate and click on the user account that has been restricted from sending outbound emails from the list.

Unblock the user

Select the 'Unblock' action and follow the on-screen prompts to confirm the removal of the restriction.

Unblock a Single Restricted Account via the Defender Portal

Processing Time: It may take up to one hour for the changes to propagate and for the user to resume sending emails.

Solution 2

Contact Support for Tenant-Wide Blocks

Use this method if the entire Microsoft 365 tenant is blocked from sending outbound emails.

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Frequently Asked Questions

Why did Microsoft 365 restrict my outbound email?

Microsoft restricts accounts when its security systems detect suspicious behavior, such as sending a high volume of spam or bulk emails, which often indicates compromised user credentials.

How long does it take to send emails again after unblocking an account?

Once an administrator removes the user from the Restricted Users portal, it generally takes about one hour for the outbound sending capabilities to be fully restored across the network.

What should I check before unblocking a restricted account?

You should reset the user's password, check for unauthorized inbox forwarding rules, review multi-factor authentication (MFA) settings, and ensure no malicious applications are linked to the account.

Microsoft Office Security Issues