Send & Receive Issues

Fix Microsoft 365 External Email Forwarding Not Working

Khadija Khan Oct 20, 2026 869 views

Question details

Users are unable to forward emails from their Microsoft 365 mailboxes to external email addresses automatically.

How to Fix Microsoft 365 External Email Forwarding That Has Stopped Working

Product: Microsoft 365
Device & OS: not provided
Scenario: Attempting to set up or maintain automatic email forwarding from a Microsoft 365 account to a personal or third-party external email address.
Observed behavior: Direct email delivery functions normally, but automated forwarding to external addresses fails or is blocked without user notification.

Before you start

Ensure you have global administrator or security administrator permissions in your Microsoft 365 tenant, as resolving this issue requires modifying organization-wide threat policies.

Solution 1Recommended

Enable Automatic Forwarding in Microsoft Defender

Modify the default outbound anti-spam policy to allow automatic external forwarding for your organization.

Microsoft periodically updates security defaults to prevent data exfiltration and spam. By default, automatic external forwarding is often disabled in the outbound anti-spam policy, which overrides user-level inbox rules.

Access the Microsoft Defender Portal

Navigate to security.microsoft.com in your web browser and log in with your Microsoft 365 administrator credentials.

Navigate to Anti-Spam Policies

In the left navigation pane, expand 'Email & collaboration', click on 'Policies & rules', select 'Threat policies', and then choose 'Anti-spam'.

Edit the Outbound Policy

Click on 'Anti-spam outbound policy (Default)' from the list. In the flyout pane that appears, scroll down and click on 'Edit protection settings'.

Enable Forwarding

Locate the 'Automatic forwarding rules' section. Change the dropdown menu from 'Automatic - System-controlled' to 'On - Forwarding is enabled'. Click 'Save' to apply the changes.

Enable Automatic Forwarding in Microsoft Defender

Policy Propagation Time: It may take up to 24 hours for changes in the anti-spam policy to fully propagate across all Microsoft 365 services and users.

Solution 2

Create an External Mail Contact in the Admin Center

If organizational policies restrict global forwarding, you can create a specific mail contact to forward messages securely.

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Frequently Asked Questions

Why did external forwarding suddenly stop working in Microsoft 365?

Microsoft frequently updates its security defaults to prevent data leaks and outbound spam. Because of this, automatic external forwarding is often disabled automatically in the global outbound anti-spam policy.

Can I enable external forwarding for just one specific user?

Yes. Instead of editing the default global policy, you can create a custom outbound anti-spam policy in the Microsoft Defender portal, enable external forwarding within it, and assign that policy exclusively to specific users or groups.

Does setting up an inbox rule in Outlook bypass the anti-spam policy?

No. Even if a user manually sets up an Inbox rule in the Outlook desktop app or Outlook on the web to forward messages, the Microsoft 365 outbound anti-spam policy will intercept and block the forwarding if it is disabled globally.

What should I do if external forwarding is enabled but emails are still failing?

You should check the message trace in the Exchange admin center to identify specific error codes. If the policy settings are correct but emails are still dropping, you will need to open a support ticket with Microsoft 365 Support.

Outlook & Email Problems