Account Security Problems

How to Fix Microsoft 365 Email Sending Restrictions Caused by Spam

Adam Davis Sep 27, 2026 869 views

Question details

An Exchange Online account has been restricted from sending outgoing emails due to exceeding sending limits or suspected spamming behavior.

How to Fix Microsoft 365 Email Sending Restrictions Caused by Spam

Product: Microsoft 365
Device & OS: not provided
Scenario: A user is unable to send emails, receiving bounce messages or restriction notices, requiring an administrator to restore sending capabilities.
Observed behavior: The account is completely blocked from sending outgoing messages and is listed as a restricted entity in the Microsoft 365 Defender portal.

Before you start

Before removing the restriction, verify that the user's account has not been compromised. Immediately change the account password, review forwarding rules, and ensure Multi-Factor Authentication (MFA) is enabled to prevent further unauthorized activity.

Solution 1Recommended

Unblock the Account via Microsoft 365 Defender Portal

This solution should be used by Microsoft 365 administrators to restore email sending capabilities after securing a blocked account.

Exchange Online automatically restricts accounts that exceed outgoing email limits or exhibit spam-like behavior to protect the overall system reputation.

Only administrators with the appropriate permissions can access the Restricted entities page to lift these outbound spam restrictions.

Sign in to Microsoft 365 Defender

Open your web browser and sign in to the Microsoft 365 Defender portal using your global administrator or security administrator credentials.

Navigate to Restricted Entities

On the left-hand navigation menu, go to Email & collaboration, then click on Review, and select Restricted entities to view the list of blocked accounts.

Select the Blocked Account

Locate the affected user account in the list. Click on the account to open the details pane on the right side of the screen.

Initiate the Unblock Process

Click the 'Unblock' button in the details pane. A wizard will appear guiding you through the necessary security recommendations.

Confirm and Submit

Follow the prompts, acknowledge that you have secured the account against compromise, and submit the unblock request.

Unblock the Account via Microsoft 365 Defender Portal

Processing Time: Restrictions are typically removed within one hour after the unblock request is submitted, provided no further suspicious activity occurs.

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Frequently Asked Questions

Why did Microsoft 365 restrict my email account from sending messages?

Microsoft automatically restricts accounts to protect its network reputation when an account exceeds outgoing message limits, sends bulk spam, or exhibits anomalous behaviors typical of a compromised account.

How long does it take for an email account to be unblocked?

Once a Microsoft 365 administrator initiates the unblock process in the Defender portal, it usually takes about one hour for the restrictions to be fully lifted and normal email flow to resume.

Can a regular user unblock their own restricted email account?

No, regular users cannot lift spam restrictions. Only a Microsoft 365 administrator with global admin or security admin permissions can access the Restricted entities page to unblock an account.

What should I do before asking my admin to unblock my account?

You should immediately change your account password, ensure Multi-Factor Authentication (MFA) is turned on, and run a thorough antivirus scan on your devices to ensure no malware is sending unauthorized emails.

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